Cross Pharmacological,Biochemical and Computational Studies of a Human Kv3.1b Inhibitor from Androctonus australis Venom

The voltage-gated K⁺ channels Kv3.1 display fast activation and deactivation kinetics and are known to have a crucial contribution to the fast-spiking phenotype of certain neurons. AahG50, as a natural product extracted from Androctonus australis hector venom, inhibits selectively Kv3.1 channels. In the present study, we focused on the biochemical and pharmacological characterization of the component in AahG50 scorpion venom that potently and selectively blocks the Kv3.1 channels. We used a combined optimization through advanced biochemical purification and patch-clamp screening steps to characterize the peptide in AahG50 active on Kv3.1 channels. We described the inhibitory effect of a toxin on Kv3.1 unitary current in black lipid bilayers. In silico, docking experiments are used to study the molecular details of the binding. We identified the first scorpion venom peptide inhibiting Kv3.1 current at 170 nM. This toxin is the alpha-KTx 15.1, which occludes the Kv3.1 channel pore by means of the lysine 27 lateral chain. This study highlights, for the first time, the modulation of the Kv3.1 by alpha-KTx 15.1, which could be an interesting starting compound for developing therapeutic biomolecules against Kv3.1-associated diseases.     

Leveraging countermeasures as a service for VoIP security in the cloud

The emergence of cloud computing is contributing to the integration of multiple services, in particular VoIP services. While the cloud has recently been used for performing security attacks targeting IP telephony, it also provides new opportunities for supporting the security of this service. In that context, we propose a risk management strategy for VoIP cloud based on security countermeasures that may be outsourced as services. We present the architecture of our solution and its components in the context of services implementing the SIP protocol. We describe the mathematical modelling supporting our approach and detail different treatment strategies for the application of countermeasures. Finally, we quantify the benefits and limits of these strategies based on extensive simulation results. When a countermeasure fails, these strategies allow us to maintain the risk level low at an additional cost of up to 7%, or to accept an additional risk of up to 12%. They can also be combined to obtain a trade‐off between cost and performance. Copyright © 2013 John Wiley & Sons, Ltd.     

Structural and dielectric behaviors for Mg0.5Co0.5Fe2O4 spinel ferrite synthesized by sol–gel route

Journal of Materials Science: Materials in Electronics - In this work, the structural and dielectric properties for Mg0.5Co0.5Fe2O4 ferrite (abbreviated as MCFO) prepared by sol–gel process...     

A fractional state space realization method with block pulse basis

In this paper, a new analytic method for the fractional state space modeling of non-integer systems is presented. The tool of orthogonal functions and particularly the block pulse basis is used jointly with their generalized operational matrices in order to establish the state space representation which is not always obvious in the fractional framework. The commensurate case which is the simplest one is firstly handled. Then, the same development is generalized to the non-commensurate case defining so a nonlinear criterion to be minimized. Examples and simulations are presented to show the usefulness of the technique.