The impact of progredient vessel and tissue stiffening for the development of metabolic syndrome

Established risk factors for the metabolic syndrome as diabetes and arterial hypertension are believed to be the cause of arteriosclerosis and subsequently following diseases like coronary heart disease, apoplexy, or chronic renal failure. Based on broad evidence from the already available experimental literature and clinical experience, an alternative hypothesis is presented that puts an increased vessel and organ stiffness to the beginning of the pathophysiological scenario. The stiffness itself is caused by a persistent activation of mechano-sensitive cation channels like the epithelial/endothelial sodium channel. A further enhancement takes place by proteins like JACD and RhoA coupled phospholipase C coupled G-protein receptors and integrins. A self-enhancing positive feedback loop by activation of YAP/TAZ signaling is a further central pillar of this theory. Further investigations are necessary to verify this hypothesis. If this hypothesis could be confirmed fundamental changes regarding the pharmacologic therapy of the diseases that are currently summarizes as metabolic syndrome would be the consequence

Elektronisch abstimmbare transistorbasierte Induktivitäten für den Hochfrequenzbereich

Die zur Verfügung stehenden Frequenzen stellen für eine zunehmende Anzahl von Anwendungen eine zentrale Ressource dar. Die effiziente Nutzung der verfügbaren Frequenzen ist erforderlich und damit die Entwicklung von frequenzagilen Sender- und Empfängerarchitekturen. Dafür können entweder mehrere Schaltungen für die jeweiligen Frequenzen parallel aufgebaut werden, oder im Sinne der fortschreitenden Miniaturisierung konfigurierbare Schaltungen verwendet werden. Die steuerbaren Bauelemente, die für konfigurierbare Schaltungen notwendig sind, sind auf vielfältige Weise realisierbar. Die vorliegende Arbeit beinhaltet den Funktionsbeweis der transistorbasierten Induktivitätsschaltung, zeigt das Potenzial des Ansatzes und stellt Richtlinien für die Dimensionierung beziehungsweise den Aufbau der Schaltung auf. Das Potenzial als symmetrische, variierbare und miniaturisierbare Induktivität im Hochfrequenzbereich für frequenzagile Anwendungen wird untersucht. Eine Literaturrecherche zum Stand der Technik beschreibt die bisher üblichen Methoden für abstimmbare Induktivitäten und ermöglicht einen Vergleich mit der Induktivitätsschaltung. Sie ist aufgrund der Möglichkeit der Integration und Miniaturisierung eine nützliche Ergänzung für die HF-Schaltungstechnik. Analytische Untersuchungen in Kombination mit numerischen Simulationsmethoden erlauben das Ableiten von präziseren Entwurfskriterien, die nach Wissen der Autorin das erste Mal auch transistorinterne Größen berücksichtigen. Die Richtlinien werden anschließend durch die Messung realisierter Schaltungen validiert, in denen symmetrisches Verhalten.Available frequencies are a central resource for an increasing number of applications. Efficient use of the available frequencies is required and thus the development of frequency-agile transmitter and receiver architectures. For this purpose, either several circuits for the respective frequencies can be built in parallel, or configurable circuits can be used in the sense of advancing miniaturization. The tunable components required for configurable circuits can be realized in a variety of ways. This paper includes the functional proof of the transistor-based inductor circuit, demonstrates the potential of the approach, and provides guidelines for realizing the circuit. The potential as a symmetrical, tunable and miniaturizable inductance in the high frequency range for frequency agile applications is investigated. A literature review on the state of the art describes the common methods used so far for tunable inductances and allows a comparison with the transistor-based inductance circuit. It is a useful addition to RF circuit design due to the possibility of integration and miniaturization. Analytical studies combined with numerical simulation methods allow the derivation of more precise design criteria, which, to the author's knowledge, are the first time that transistor-internal quantities are considered. The guidelines are then validated by measuring realized circuits, and symmetrical behavior, a wide tuning range of inductance, and a wider usable frequency range are demonstrated. The results presented range from achievable tunable inductance values between 3.4 uH and 6.5 uH at frequencies up to 5 MHz, to circuits whose tuning ranges between 30 nH to 50 nH for a usable frequency range between 50 MHz and 500 MHz

The action of ammonium on postsynaptic inhibition of cat spinal motoneurons

Potential changes were investigated which follow the intra- and extracellular electrophoretic injection of NH4 + and also the intravenous application of neutral ammonium salts. The common effect found in all kinds of application is a depolarizing shift of the IPSP-equilibrium potential (EIPSP) towards the resting potential. Inhibitory transmission is preserved but produces considerably reduced hyperpolarizing potential changes at normal resting potentials. In addition, ammonium ions produce short term shifts of resting and overshoot potentials with intracellular application. The latter changes can be explained under the assumption that NH4 + partly substitutes for Na+ as for the action potential generation.The observed reversible reduction of EIPSP has high sensitivity towards extracellular and systemic NH4 + application as compared to intracellular injection. The time course of the depolarizing shift of EIPSP, especially its restitution, was shortest in extracellular application. It is suggested that ammonium release from the internal site produces the long term effects observed on the IPSP after intracellular injection. The externally effective dosages correspond to intracerebral NH4 +-concentrations which are reported for preconvulsive states of various kinds of metabolically induced epilepsies