Ce-doped MgO films on AZ31 alloy substrate for biomedical applications: preparation, characterization and testing

Magnesium ions, MgO nanoparticles and thin films, magnesium alloys and cerium compounds are materials intensively studied due to their corrosion protection, antibacterial and pharmacological properties. In this work, we have designed, prepared and investigated, novel thin films of MgO doped with cerium, deposited on Mg alloy (AZ31) for temporary implants, in order to enhance their life time. More precisely, we report on microstructure and corrosion behavior of MgO pure and doped with 0.1 at % Ce films, fabricated by sol-gel route coupled with spin-coating technique, on AZ31 alloy substrate. A modified sol-gel method that start from magnesium acetylacetonate, cerium nitrate and 2-methoxyethanol (as a stabilizer for the sol) was been used successfully for cerium doped MgO sol precursor preparation. The structure and morphology of the surface of the coatings, before and after immersion for 7-30 d in Hank's solution at 37 °C, were characterized by x-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscope, x-ray photoelectron spectroscopy and Fourier infrared transmittance spectrum (FT-IR). A comparison between the corrosion protection of undoped MgO and MgO doped with 0.1 at % Ce coatings on the AZ31 alloy substrate is performed by electrochemical tests and immersion tests using open circuit potential and electrochemical impedance spectroscopy in Hank's solution, at 37 °C. The electrochemical results showed that the protection of the AZ31 alloy substrate against corrosion was better with the doped with 0.1 at % Ce MgO film deposited than with pure MgO coting. The investigations of the films after immersion in Hank's solution, at 37 °C, for 7, 21 and 30 d indicated that the grown layer on the film is bone like apatite that suggests a good bioactivity of 0.1 at % Ce-doped MgO coating. Our work demonstrates that the performance corrosion protection of the biodegradable magnesium alloys used for orthopedic applications, in simulated physiological environments (Hank and Ringer) can be enhanced through coating with Ce3+doped MgO sol-gel thin film.

Lead-Free BNT-BT0.08/CoFe2O4 Core-Shell Nanostructures with Potential Multifunctional Applications

Herein we report on novel multiferroic core–shell nanostructures of cobalt ferrite (CoFe₂O₄)–bismuth, sodium titanate doped with barium titanate (BNT–BT_0.08), prepared by a two–step wet chemical procedure, using the sol–gel technique. The fraction of CoFe₂O₄ was varied from 1:0.5 to 1:1.5 = BNT–BT_0.08/CoFe₂O₄ (molar ratio). X–ray diffraction confirmed the presence of both the spinel CoFe₂O₄ and the perovskite Bi_0.5Na_0.5TiO₃ phases. Scanning electron microscopy analysis indicated that the diameter of the core–shell nanoparticles was between 15 and 40 nm. Transmission electron microscopy data showed two–phase composite nanostructures consisting of a BNT–BT_0.08 core surrounded by a CoFe₂O₄ shell with an average thickness of 4–7 nm. Cole-Cole plots reveal the presence of grains and grain boundary effects in the BNT–BT_0.08/CoFe₂O₄ composite. Moreover, the values of the dc conductivity were found to increase with the amount of CoFe₂O₄ semiconductive phase. Both X-ray photoelectron spectroscopy (XPS) and Mössbauer measurements have shown no change in the valence of the Fe³⁺, Co²⁺, Bi³⁺ and Ti⁴⁺ cations. This study provides a detailed insight into the magnetoelectric coupling of the multiferroic BNT–BT_0.08/CoFe₂O₄ core–shell composite potentially suitable for magnetoelectric applications.

P1476Global longitudinal strain assessed by 2-D speckle tracking echocardiography identifies myocardial viability and predicts LV function and remodeling after acute MI with systolic dysfunction

Aims

To assess whether two-dimensional speckle-tracking echocardiography (2D-STE) could (1) identify myocardial viability in comparison with late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR); (2) predict global left ventricular (LV) functional recovery and remodeling and (3) assess prognosis after acute myocardial infarction (MI) with LV systolic dysfunction.

Methods

Seventy one first STEMI patients with LVEF ≤45%, treated with acute percutaneous coronary intervention, underwent 2D-echocardiography for 2D-STE analysis and LGE CMR between 2 and 45 days after STEMI. Segments were defined as viable when transmural LGE extension was <50% and non viable when transmural LGE extension was ≥50%. At 8-month follow-up, transthoracic echocardiography was repeated to determine global LV functional recovery (increase in LVEF ≥5%) and LV remodeling (increase in end-systolic volume >15%) (n=30) and clinical outcomes were obtained (n=46).

Results

Global longitudinal strain (GLS) was lower in non viable than in viable infarct segments (−6.6±6.1% vs −10.3±5.9%, p<0.0001) and in viable infarct segments than in normal segments (−10.3±5.9% vs −14.5±6.4%, p<0.0001). GLS >−12% had sensitivity of 78% and specificity of 69% to identify non viable segments (area under the curve (AUC), 0.79; 95% confidence interval (CI), 0.77–0.81, p<0.0001). GLS >−11.3% had sensitivity of 53% and specificity of 100% to predict the absence of global functional improvement (AUC=0.73 (CI: 0.55–0.87) p=0.01) at 8-month follow-up. GLS <−12.5% predicted the absence of adverse LV remodeling at 8-month follow-up with a sensitivity of 100% and a specificity of 54% (AUC=0.83 (CI: 0.66–0.94) p<0.0001). GLS >−11.5% was associated with a poor prognosis.

Conclusions

In patients with recent first acute MI with LV systolic dysfunction, GLS assessed by 2D-STE: (1) is able to identify non viable segments in comparison with LGE CMR, (2) allows prediction of LV global functional recovery and LV remodeling at 8-month follow-up and (3) provides strong prognostic information, independently of LVEF.

Evaluation du potentiel productif des exploitations agricoles dans les monts de Tlemcen (nord-ouest de l’Algérie)

La population montagnarde algérienne reste tributaire surtout d’une agriculture fragile. À cet effet, le présent travail consiste à effectuer une évaluationapprofondiede la situation actuelle des exploitations agricoles, qui sont fortement fragilisées par différentes contraintesdans les monts de Tlemcen, afin d’évaluer leur potentiel productif. Les résultats obtenus ont montréque les exploitations enquêtées quoiqu’elles appartiennent à un même ensemble montagneux, elles se distinguent par des particularités différentes d’une région à une autre. Certaines exploitations sont orientées vers le modeld’exploitation familiale à cause de leur morcellement répété et du manque de main d’œuvre salariée. D’autres exploitations sont obligées de développer une stratégie de survie basée essentiellement sur une céréaliculture extensive combinée surtout avec l’élevage ovin. Dans l’ensemble, les moyens de production actuels de toutes les exploitations enquêtées sont insuffisants pour qu’elles puissent résister au climat irrégulier, à la configuration difficile des terrains et aux fluctuations du marché.

Purification and identification of two putative autolytic sites in human calpain 3 (p94) expressed in heterologous systems

Human muscle-specific calpain (CAPN3) was expressed in two heterologous systems: Sf9 insect cells and Escherichia coli cells. Polyclonal antibodies were prepared against peptides whose sequences were taken from the three unique regions of human CAPN3, namely NS, IS1, and IS2, which are not found in other members of the calpain family. Western blot analysis using these antibodies revealed that CAPN3 was well expressed in both systems. However, considerable rapid degradation of the expressed CAPN3 was observed in both Sf9 and E. coli cells. These antibodies were therefore also used to detect CAPN3 and its degradation products in human and rat muscles, as well as to detect the protein throughout the purification of the recombinant His-tagged human CAPN3 by Ni2+ affinity chromatography and by immunopurification over immobilized antibody. An alternative purification procedure was used for purification of all putative CAPN3 immunoreactive fragments by combining SDS-PAGE and hydroxyapatite chromatography. Two fragments of CAPN3 of approximately 55 kDa were purified, and their N-terminal amino acid sequencing demonstrated that cleavage of CANP3 occurred between residues 30-31 and 412-413, thus providing the first evidence for the localization of putative autolytic sites in this enzyme.

Association of the cytoplasmic domain of intercellular-adhesion molecule-1 with glyceraldehyde-3-phosphate dehydrogenase and beta-tubulin

To elucidate the molecular mechanisms of the transendothelial migration of leukocytes, we attempted to identify the cellular proteins capable of interaction with the cytoplasmic domain of the intercellular adhesion molecule-1 (ICAM-1) in a rat brain microvessel endothelial cell line (RBE4 cells). A 27-amino-acid synthetic peptide, corresponding to the cytoplasmic domain of rat ICAM-1, was covalently linked to a Sepharose matrix. Upon affinity chromatography of RBE4 cell cytosol, several ICAM-1-interacting proteins were specifically eluted by the soluble peptide. Two of these proteins have been identified by microsequencing as the cytoskeletal protein beta-tubulin and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GraP-DH). Experiments carried out with purified GraP-DH or CNBr fragments of GraP-DH indicated that binding to the ICAM-1 matrix was mediated by the C-terminal domain of GraP-DH, containing the binding site of the cofactor NAD+, and that NAD+ could compete with this binding. Using a series of ICAM-1 C-terminal truncated peptides, we could demonstrate that (a) the nitric-oxide-induced covalent linkage of NAD+ to GraP-DH was impaired by these peptides, (b) the glycolytic activity of GraP-DH was drastically inhibited by a truncated peptide containing the 15 C-terminal residues, (c) nitric oxide appeared to prevent this inhibition. Together, our results demonstrate that GraP-DH specifically associates with the isolated ICAM-1 cytoplasmic domain. Since GraP-DH is known as a microtubule bundling protein, these findings suggest that, in a cellular environment, GraP-DH may behave as an adaptor molecule by linking ICAM-1 to the microtubule network. The role of nitric oxide in the modulation of this interaction deserves further investigation.

Simulation of the inhibitory cystatin surface by a synthetic peptide

An inhibitory dodecameric peptide was designed which tentatively mimics the inhibitory site of cystatin C-like structures. Succinylated and mansylated derivatives were also synthesised and assayed for their inhibiting properties towards papain and rat cathepsins B, H and L. All peptides preferentially inhibit cathepsin L and papain as their naturally occurring inhibitor model. A significant increase in inhibition was obtained after mansylation of the crude peptide with Ki values in the micromolar or 0.1 micromolar range. The use and interest of such peptide inhibitors are discussed.

Microvascular free jejunal transfer reconstruction following pharyngo-laryngectomy

Case histories of six patients who underwent pharyngo-laryngectomy for hypopharyngeal carcinoma with jejunal microvascular free transfer reconstruction are presented. The potential advantages of this technique over other reconstructive methods are discussed.