H2O2 detection from intact mitochondria as a measure for one-electron reduction of dioxygen requires a non-invasive assay system11Dedicated to Prof. E. Elstner, on the occasion of his 60th anniversary.

AbstractEvaluation of the existence of superoxide radicals (O⋅−2), the site of generation and conditions required for one-e− transfer to oxygen from biological redox systems is a prerequisite for the understanding of the deregulation of O2 homeostasis leading to oxidative stress. Mitochondria are increasingly considered the major O⋅−2 source in a great variety of diseases and the aging process. Contradictory reports on mitochondrial O⋅−2 release prompted us to critically investigate frequently used O⋅−2 detection methods for their suitability. Due to the impermeability of the external mitochondrial membrane for most constituents of O⋅−2 detection systems we decided to follow the stable dismutation product H2O2. This metabolite was earlier shown to readily permeate into the cytosol. With the exception of tetramethylbenzidine none of the chemical reactants indicating the presence of H2O2 by horseradish peroxidase-catalyzed absorbance change were suited due to solubility problems or low extinction coefficients. Tetramethylbenzidine-dependent H2O2 detection was counteracted by rereduction of the dye through e− carriers of the respiratory chain. Although the fluorescent dyes scopoletin and homovanillic acid were found to be suited for the detection of mitochondrial H2O2 release, fluorescence change was strongly affected by mitochondrial protein constituents. The present study has resolved this problem by separating the detection system from H2O2-producing mitochondria

Programming MPSoC platforms: Road works ahead

This paper summarizes a special session on multicore/multi-processor system-on-chip (MPSoC) programming challenges. The current trend towards MPSoC platforms in most computing domains does not only mean a radical change in computer architecture. Even more important from a SW developer´s viewpoint, at the same time the classical sequential von Neumann programming model needs to be overcome. Efficient utilization of the MPSoC HW resources demands for radically new models and corresponding SW development tools, capable of exploiting the available parallelism and guaranteeing bug-free parallel SW. While several standards are established in the high-performance computing domain (e.g. OpenMP), it is clear that more innovations are required for successful\ud deployment of heterogeneous embedded MPSoC. On the other hand, at least for coming years, the freedom for disruptive programming technologies is limited by the huge amount of certified sequential code that demands for a more pragmatic, gradual tool and code replacement strategy

THE CONVERGENCE OF THE OSPF ROUTING PROTOCOL

In this paper an OSPF convergence time prediction model is introduced. It is based on examining the behaviour OSPF and on the analysis of the generated data by OSPF flooding. The model was validated and refined by tests and experiments on a test network built for this work. The resultant model can be used to predict the effect and convergence of a change in an OSPF network. This feature is very usable for pre-emptive network management and network planning

Effect of α-lipoic acid and dihydrolipoic acid on ischemia/reperfusion injury of the heart and heart mitochondria

AbstractThe aim of the present study was to evaluate a possible interference of a-lipoic acid (LA) or its reduced form (dithiol dihydrolipoic acid = DHLA) in the cardiac ischemia/reperfusion injury both at the level of the intact organ and at the subcellular level of mitochondria. In order to follow the effect of LA on the ischemia/reperfusion injury of the heart the isolated perfused organ was subjected to total global ischemia and reperfusion in the presence and absence of different concentrations of LA. Treatment with 0.5 μM LA improved the recovery of hemodynamic parameters; electrophysiological parameters were not influenced. However, application of 10 μM LA to rat hearts further impaired the recovery of hemodynamic functions and prolonged the duration of severe rhythm disturbances in comparison to reperfusion of control hearts. Treatment of isolated mitochondria with any concentration of DHLA could not prevent the impairment of respiratory-linked energy conservation caused by the exposure of mitochondria to `reperfusion' conditions. However, DHLA was effective in decreasing the formation and the existence of mitochondria) superoxide radicals (O2−) Apart from :ts direct 02-scavenging activities DHLA was also found to control mitochondria) O2− formation indirectly by regulating redox-cycling ubiquinone. It is suggested that impairment of this mitochondria) O2− generator mitigates postischemic oxidative stress which in turn reduces damage to hemodynamic heart function

Nonlinear dynamics of the classical isotropic Heisenberg antiferromagnetic chain: the sigma model sector and the kink sector

We identify two distinct low-energy sectors in the classical isotropic antiferromagnetic Heisenberg spin-S chain. In the continuum limit, we show that two types of rotation generators arise for the field in each sector. Using these, the Lagrangian for sector I is shown to be that of the nonlinear sigma model. Sector II has a null Lagrangian; Its Hamiltonian density is just the Pontryagin term. Exact solutions are found in the form of magnons and precessing pulses in I and moving kinks in II. The kink has `spin' S. Sector I has a higher minimum energy than II.Comment: 4 page