Nitroxide spin labels and EPR spectroscopy: A powerful association for protein dynamics studies.

Site-Directed Spin Labelling (SDSL) technique is based on the attachment of a paramagnetic label onto a specific position of a protein (or other bio-molecules) and the subsequent study by Electron Paramagnetic Resonance (EPR) spectroscopy. In particular, continuous-wave EPR (cw-EPR) spectra can detect the local conformational dynamics for proteins under various conditions. Moreover, pulse-EPR experiments on doubly spin-labelled proteins allow measuring distances between spin centres in the 1.5-8 nm range, providing information about structures and functions. This review focuses on SDSL-EPR spectroscopy as a structural biology tool to investigate proteins using nitroxide labels. The versatility of this spectroscopic approach for protein structural characterization has been demonstrated through the choice of recent studies. The main aim is to provide a general overview of the technique, particularly for non-experts, to spread the applicability of this technique in various fields of structural biology.

SimLabel: a graphical user interface to simulate continuous wave EPR spectra from site-directed spin labeling experiments.

Site-directed spin labeling (SDSL) combined with continuous wave electron paramagnetic resonance (cw EPR) spectroscopy is a powerful technique to reveal, at the residue level, structural transitions in proteins. SDSL-EPR is based on the selective grafting of a paramagnetic label on the protein under study, followed by cw EPR analysis. To extract valuable quantitative information from SDSL-EPR spectra and thus give reliable interpretation on biological system dynamics, numerical simulations of the spectra are required. Such spectral simulations can be carried out by coding in MATLAB using functions from the EasySpin toolbox. For non-expert users of MATLAB, this could be a complex task or even impede the use of such simulation tool. We developed a graphical user interface called SimLabel dedicated to run cw EPR spectra simulations particularly coming from SDSL-EPR experiments. Simlabel provides an intuitive way to visualize, simulate, and fit such cw EPR spectra. An example of SDSL-EPR spectra simulation concerning the study of an intrinsically disordered region undergoing a local induced folding is described and discussed. We believe that this new tool will help the users to rapidly obtain reliable simulated spectra and hence facilitate the interpretation of their results. Copyright © 2017 John Wiley & Sons, Ltd.

A rare localization of cerebral venous sinus thrombosis. Case report.

In this work the Authors report their experience on the treatment of a case of cavernous venous sinus thrombosis. The diagnosis is clinical and neuroradiological, CT, MRN, cerebral angiography and orbital venography have aided in establishing the diagnosis during life. Very interesting is the therapeutic approach.

From surgery to neurosurgery: our experience on the efficacy of fleece-bound sealing (TachoSil®) for dural repair.

AIM: To report on our routine use of TachoSil® for dural repair in neurosurgical practice. METHOD: TachoSil® has been applied in different fields of surgery thus far. When using TachoSil®, fibrinogen and thrombin is provided locally at the site of the dural defects. Upon contact with fluid, the clotting factors of TachoSil® dissolve and form a fibrin network, which glues the collagen sponge to the wound surface. RESULTS: In our experience, TachoSil® was found to be effective as support for the suture of the dura in patients undergoing spinal and cranial neurosurgical operations. Two illustrative examples are shown. CONCLUSIONS: Our procedure showed that closing the dural defect with TachoSil® is a technically simple, reliable and safe method for patients. Indeed, no post-operative cerebrospinal fluid leakage was observed. Nonetheless, further studies with larger sample size are warranted to confirm the efficacy of TachoSil® patches for dural repair.

Amphiphilic poly(vinyl alcohol) derivatives as complexing agents for fenretinide.

Poly(vinyl alcohol) (PVA) substituted with oleyl chains and tetraethyleneglycol monoethyl ether chains (TEGMEE) at 1.5% and 1% degrees of substitution respectively (mol of substituent to mol of hydroxyvinyl monomer) has previously been shown to self-assemble in water, providing aggregates selectively cytotoxic toward tumor cells vs normal cells. These polymers have also been shown to increase the long-term survival of nude mice injected with both human and murine neuroblastoma cell lines. In the present work, we changed the substitution degree of the oleyl chains on the poly(vinyl alcohol) backbone and maintained constant at 1% the degree of TEGMEE substitution. We evaluated the main physicochemical characteristics of the final polymers, their cytotoxicity toward tumor cells, and their complexing ability for hydrophobic molecules. The aim was to investigate the possibility of improving intrinsic antitumor efficacy of the polymer by changing the degree of oleyl chain substitution and further increase activity by complexation with antitumor drugs. The polymers were prepared at oleyl chain substitution degrees ranging from 0.5 to 3% (mol of substituent to mol of hydroxyvinyl monomer). The most active was again the 1.5% substituted polymer. It was further characterized by exhibiting the highest complexing ability toward hydrophobic molecules allowing the formation of a complex with fenretinide (HPR). The polymer-HPR complex was stable in aqueous environment and released the free drug prevalently in the presence of fluid hydrophobic phases. It was cytotoxic toward tumor cells with minimal activity toward normal cells. Antitumor activity exceeded that of the separate complex components resulting from the concomitant effect of the polymer and the HPR solubilized by complexation.