The voltage of the fuel cell must be measured during the test phase to characterize and condition it. Similarly, monitoring the fuel cell during its operation in series has many advantages. The CVM is a permanent and individualized measurement system for each cell. DAM has developed a universal system that can be connected to any type of bipolar plate. In addition, its modularity allows it to adapt to the number of cells and the fuel cell voltage, while compensating deformation phenomena. Moreover, its electronic architecture also allows a great modularity while proposing additional functions of diagnosis and measurements of insulation and short-circuit. These features are essential for the mass production of the CVM and the automated assembly of the CVM on the fuel cell, ensuring a cost competitive solution. / Die Spannung der Brennstoffzelle muss während der Testphase gemessen werden, um sie zu charakterisieren und zu konditionieren. Auch die Überwachung der Brennstoffzelle während ihres Serienbetriebs hat viele Vorteile. Das CVM ist ein permanentes und individuelles Messsystem für jede einzelne Zelle. DAM hat ein universelles System entwickelt, das an jede Art von Bipolarplatte angeschlossen werden kann. Außerdem kann es aufgrund seiner Modularität an die Anzahl der Zellen und die Brennstoffzellenspannung angepasst werden, wobei Verformungsphänomene kompensiert werden. Darüber hinaus ermöglicht seine elektronische Architektur eine große Modularität und bietet zusätzliche Diagnosefunktionen und Messungen für Isolation und Kurzschluss. Diese Merkmale sind für die Massenproduktion des CVM und die automatisierte Montage des CVM auf der Brennstoffzelle von wesentlicher Bedeutung und ermöglichen eine kostengünstige Lösung.

Pannexins are vertebrate proteins with limited sequence homology to the invertebrate gap junction proteins, the innexins. However, in contrast to innexins and the vertebrate connexins, pannexins do not form gap junction channels. Instead they appear to solely function as unpaired membrane channels allowing the flux of molecules, including ATP, across the plasma membrane. We provided additional evidence for their ATP release function by demonstrating that the connexin mimetic peptides, which were thought to inhibit ATP release through connexin channels, do not inhibit their host connexin channels but instead inhibit pannexin1 channels by a mechanism of steric block. Therefore, the inhibitory effects of mimetic peptides on ATP release may represent supporting evidence for a role of pannexin1 in ATP release. We also analyzed the pore structure of pannexin1 channels with the Substituted Cysteine Accessibility Method. The thiol reagents MBB and MTSET reacted with several positions in the external portion of the first transmembrane segment and the first extracellular loop. In addition, MTSET reactivity was found in the internal portion of TM3. These data suggest that portions of TM1, E1 and TM3 line the pore of pannexin1 channels. Thus, the pore structure of pannexin1 is similar to that of connexin channels.

The phosphoinositide 3-kinases (PI3K/Akt) dependent signaling pathway plays an important role in cardiac function, specifically cardiac contractility. We have reported that sepsis decreases myocardial Akt activation, which correlates with cardiac dysfunction in sepsis. We also reported that preventing sepsis induced changes in myocardial Akt activation ameliorates cardiovascular dysfunction. In this study we investigated the role of PI3K/Akt on cardiomyocyte function by examining the role of PI3K/Akt-dependent signaling on [Ca 2+]i, Ca2+ transients and membrane Ca2+ current, ICa, in cultured murine HL-1 cardiomyocytes. LY294002 (120 μM), a specific PI3K inhibitor, dramatically decreased HL-1 [Ca 2+]i, Ca2+ transients and ICa. We also examined the effect of PI3K isoform specific inhibitors, i.e. α (PI3-kinase α inhibitor 2; 28 nM); ? (TGX-221; 100 nM) and γ (AS-252424; 100 nM), to determine the contribution of specific isoforms to HL-1 [Ca 2+]i regulation. Pharmacologic inhibition of each of the individual PI3K isoforms significantly decreased [Ca2+]i, and inhibited Ca 2+ transients. Triciribine (120 μM), which inhibits AKT downstream of the PI3K pathway, also inhibited [Ca2+]i, and Ca 2+ transients and ICa. We conclude that the PI3K/Akt pathway is required for normal maintenance of [Ca2+]i in HL-1 cardiomyocytes. Thus, myocardial PI3K/Akt-PKB signaling sustains [Ca 2+]i required for excitation-contraction coupling in cardiomyoctyes.

The dissertation thesis deals with the synthesis and design of active frequency filters using current (CC) and voltage (VC) conveyors, or current active elements CMI (Current Mirror and Inverter), MCMI (Multi-output CMI) and PCA (Programmable Current Amplifier). As introduction, these active elements are described as suitable for the design of the circuits working in the voltage-, current,- ,and mixed-mode, or in pure current-mode speaking about the current active elements. The new frequency filter structures presented in this thesis using the above mentioned active elements were designed by the generalized autonomous circuit method, transformation cells and signal flow-graph theory. The generalized autonomous circuit method is based on full admittance network to which generalized active elements are connected. The described admittance networks can be used for other active elements. The next method is based on the transformation cells that subsequently are used for the design of synthetic elements with higher-order imittance. Original conditions for the design of such blocks are given that lead to maximal simplicity of the final structure with minimal number of passive and active elements. For effective usage of another method utilizing signal flow-graphs, new reduced graphs of chosen active elements are given. Their usage leads to direct function blocks synthesis with required properties. The functionality and behavior of chosen circuit solutions have been verified by analyses in simulation programs. The active elements were simulated by the universal current conveyor (UCC) or universal voltage conveyors (UVC) that were designed at the FEEC, BUT in cooperation with AMI Semiconductor Design Centre Brno with the CMOS 0.35 m technology. These active elements have been also used for the realization of chosen filter structures. The experimental measurements were performed in the in the frequency range 10 KHz to 100 MHz.