Development of magnetically active scaffolds for bone regeneration

This work reports on the synthesis, with the thermally induced phase separation (TIPS) technique, of poly (L-lactide) (PLLA) scaffolds containing Fe-doped hydroxyapatite (FeHA) particles for bone regeneration. Magnetization curves and X-ray diffraction indicate two magnetic particle phases: FeHA and magnetite Fe3O4. Magnetic nanoparticles (MNPs) are approximately 30 ± 5 nm in width and 125 ± 25 nm in length, and show typical ferromagnetic properties, including coercivity and rapid saturation magnetization. Scanning electron microscopy (SEM) images of the magnetic scaffolds reveal their complex morphology changes with MNP concentration. Similarly, at compositions of approximately 20% MNPs, the phase separation changes, passing from solid–liquid to liquid–liquid as revealed by the hill-like structures, with low peaks that give the walls in the SEM images a surface pattern of micro-ruggedness typical of nucleation mechanisms and growth. In vitro degradation experiments, carried out for more than 28 weeks, demonstrated that the MNPs delay the scaffold degradation process. Cytotoxicity is appreciated for FeHA content above 20%.This work was supported by the University of The Basque Center and the Portuguese Foundation for Science and Technology (FCT) under the framework Strategic Funding UID/FIS/04650/ UID/BIA/04050/2013, and UID/BIO/04469. S.R. would like to the FCT for the SFRH/BD/111478/2015 grant. The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) under the project MAT2016-76039-C4-3-R (AEI/FEDER, UE)info:eu-repo/semantics/publishedVersio

Cerebellar-dependent delay eyeblink conditioning in adolescents with Specific Language Impairment

Cerebellar impairments have been hypothesized as part of the pathogenesis of Specific Language Impairment (SLI), although direct evidence of cerebellar involvement is sparse. Eyeblink Conditioning (EBC) is a learning task with well documented cerebellar pathways. This is the first study of EBC in affected adolescents and controls. 16 adolescent controls, 15 adolescents with SLI, and 12 adult controls participated in a delay EBC task. Affected children had low general language performance, grammatical deficits but no speech impairments. The affected group did not differ from the control adolescent or control adult group, showing intact cerebellar functioning on the EBC task. This study did not support cerebellar impairment at the level of basic learning pathways as part of the pathogenesis of SLI. Outcomes do not rule out cerebellar influences on speech impairment, or possible other forms of cerebellar functioning as contributing to SLI

Polylactide microparticles prepared by double emulsion-evaporation 2 : Effect of the poly(lactide-co-glycolide) composition on the stability of the primary and secondary emulsions

Polylactide and copolymers with glycolide have been used as coating polymers in the microencapsulation technique based on the W1/o/w2 double emulsion-evaporation method. Stability of the primary emulsion is of critical importance and clearly predetermines the internal morphology of the microspheres, in agreement with the very fast hardening of the oil phase (CH2Cl2) as soon as the primary emulsion is dispersed in water. When the peptide or' protein to be encapsulated is able to interact with the coating polymer and possibly with the surfactant, the stabilization mechanism of the primary emulsion is very complex. It has been shown that the interaction of BSA (bovine serum albumin) with the polyester is as strong as the glycolide content is high, which results in the formation of a solid film at the w1/o interface and in a high emulsion stability. Addition of a surfactant, such as poloxamer 188, in the oil phase has a deleterious effect on both the emulsion stability and the internal structure of the microspheres. Use of a dye tracer in the internal aqueous phase was not useful in probing the double emulsion stability and the encapsulation efficiency, because of specific interactions between the dye (indigocarmine) and the coating polyester

Biodegradable and macroporous polylactide implants for cell transplantation : 1. Preparation of macroporous polylactide supports by solid-liquid phase separation

Freeze-drying of polylactide solutions in 1,4-dioxane has been studied as a way to produce microcellular foams. The thermally induced phase separation has been studied in relation to several processing and formulation parameters. The effects of polymer concentration, chain stereoregularity, polymer molecular weight and cooling rate have been investigated in connection with the porous morphology and the physico-mechanical characteristics of the final foams. As a rule, bundles of channels are formed with a diameter of ~100 μ.m. They have a preferential orientation that fits the cooling direction. A porous substructure (~10 μm) is observed in the internal walls of the tubular macropores. Variations in this general porous morphology-and particularly in the porosity, density, solvent residue, mechanical resistance and degree of regularity in the spatial organization of pores-have been observed when polymer concentration in 1,4-dioxane and polylactide stereoregularity are changed. As expected, cooling rate has a strong effect on the foam morphology, which is essentially controlled by the solvent crystallization. Pores are nothing but the fingerprints of 1,4-dioxane crystallites

Polylactide Microparticles Prepared by Double Emulsion/Evaporation Technique. I. Effect of Primary Emulsion Stability

peer reviewedThe process of microencapsulation of proteins by double emulsion-evaporation in a matrix of polylactide (PLA) can be divided into three successive steps: first, an aqueous solution of the active compound is emulsified into an organic solution of the hydrophobic coating polymer; second, this primary water-in-oil (w/o) is dispersed in water with formation of a double water-oil-water emulsion (w/o/w), third, the organic solvent is removed with formation of solid microparticles. This paper focuses of the effect of primary emulsion stability on the morphology and properties of polylactide microparticles loaded with bovine serum albumin (BSA) used as model drug

Image analysis, impedance spectroscopy and mercury porosimetry characterisation of freeze-drying porous materials

Image analysis and impedance spectroscopy have been used as potential tools for the characterization of the texture of ultramacroporous PLA foams prepared by freeze-drying. It has been shown that these two techniques actually provide valuable information on the structure of this material. They are complementary to mercury porosimetry, which does not allow morphological details to be distinguished. Image analysis of SEM micrographs of transverse cross-sections at two different magnifications gave information on both the macroporosity (1 μm 10 μm). Impedance spectroscopy was used to investigate the transport properties of the three-dimensional porous matrices by measurement of ionic conductio

Role of the Striatum and the Cerebellum in Motor Skill Acquisition

Motor skill acquisition was investigated in patients with Parkinson's disease (PD) or cerebellar dysfunction using two sensory-guided tracking tasks. The subjects had to learn to track a visual target (a square) on a computer screen by moving a joystick under two different conditions. In the unreversed task, the horizontal target movements were semi-predictable and could be anticipated. In the reversed task, the horizontal movements of a pointer which had to be kept within the target square were mirror-reversed to the joystick movements. PD patients showed intact learning of the semi-predictable task and reduced learning of the mirror-reversed task; patients with cerebellar dysfunction showed the opposite pattern. These findings are discussed in relation to the differential contribution of the cerebellum and the striatum to motor skill acquisition: the cerebellum appears to participate in the implementation of anticipatory movements, whereas the striatum may be critically involved in types of motor learning which require a high degree of internal elaboration