Scaffold with controlled porosity constitute a cornerstone in tissue engineering, as a physical support for cell adhesion and growth. In this work, scaffolds of polycaprolactone were synthesized by a modified particle leaching method in order to control porosity and pore interconnectivity; the aim is to observe their influence on the mechanical properties and, in the future, on cell adhesion and proliferation rates. Low molecular weight PEMA beads with an average size of 200 microm were sintered with various compression rates in order to obtain the templates (negatives of the scaffolds). Then the melt polycaprolactone was injected into the porous template under nitrogen pressure in a custom made device. After cooling and solidifying of the melt polymer, the porogen was removed by selective dissolution in ethanol. The porosity and morphology of the scaffold were studied as well as the mechanical properties. Porosities from 60% to 85% were reached; it was found that pore interconnectivity logically increases with increasing porosity, and that mechanical strength decreases with increasing porosity. Because of their interesting properties and interconnected structure, these scaffolds are expected to find useful applications as a cartilage or bone repair material.

A role for the nucleotide-binding oligomerization domain 2 (NOD2) receptor in pulmonary innate immune responses has recently been explored. In the present study, we investigated the role that NOD2 plays in human alveolar macrophage innate responses and determined its involvement in the response to infection with virulent Mycobacterium tuberculosis. Our results showed that NOD2 was expressed in human alveolar macrophages, and significant amounts of IL-1β, IL-6, and TNF-α were produced upon ligand recognition with muramyldipeptide (MDP). NOD2 ligation induced the transcription and protein expression of the antimicrobial peptide LL37 and the autophagy enzyme IRGM in alveolar macrophages, demonstrating a novel function for this receptor in these cells. MDP treatment of alveolar macrophages improved the intracellular growth control of virulent M. tuberculosis; this was associated with a significant release of TNF-α and IL-6 and overexpression of bactericidal LL37. In addition, the autophagy proteins IRGM, LC3 and ATG16L1 were recruited to the bacteria-containing autophagosome after treatment with MDP. In conclusion, our results suggest that NOD2 can modulate the innate immune response of alveolar macrophages and play a role in the initial control of respiratory M. tuberculosis infections.Keywords: Alveolar macrophage r Autophagy r Innate immunity r NOD2 r Tuberculosis Supporting Information available online IntroductionThe recognition of pathogen-associated molecular patterns by innate immune receptors is essential for the initiation and coordination of the immune mechanisms responsible for host proCorrespondence: Dr. Eduardo Sada e-mail: eduardosadadiaz@yahoo.com tection against lung-invading pathogens [1]. The innate immune recognition is based on a limited repertoire of pattern recognition receptors, which sense conserved microbial components known as pathogen associated molecular patterns. The pattern recognition receptors include the members of the Toll-like receptor (TLR) family and the nucleotide-binding oligomerization domain (NOD) proteins (NOD-like receptors, NLRs), among others [2,3].The NLR proteins have been demonstrated to play an important role in the defense against respiratory agents, includingwww.eji-journal.eu Eur. J. Immunol. 2012. 42: 880-889 Immunity to Infection 881Pseudomonas aeruginosa, Streptococcus pneumoniae, Legionella pneumophila, and Mycobacterium tuberculosis [1,4,5]. The NOD proteins, members of the NLR family, are cytoplasmic receptors implicated in the recognition of bacterial molecules produced during the synthesis and/or degradation of peptidoglycan. Specifically, NOD2 senses the cytosolic presence of muramyldipeptide (MDP) [6,7]. Activation of NOD2 by bacterial products can stimulate two major signaling pathways to activate caspase-1 and pro-inflammatory responses, including the NF-κB pathway and the inflammasome pathway [5]. Upon ligand recognition, NOD2 activates the receptor-interacting protein-2 kinase (Rip2), which forms a multiprotein complex via its caspase activation...

The crystallization kinetics of poly(l-lactide), PLLA, is slow enough to allow a quasi-amorphous polymer to be obtained at low temperature simply by quenching from the melt. The PLLA crystallization process was followed by differential scanning calorimetry and optical microscopy after nucleation isothermal treatments at temperatures just below (53 degrees C) and just above (73 degrees C) the glass transition temperature. The crystallization exotherm shown in the heating thermograms shifts toward lower temperatures as the annealing time at 73 degrees C increases. The same effect is shown to a lesser extent when the sample nucleates at 53 degrees C, showing the ability to nucleate in the glassy state, already shown in other polymers. The shape of the DSC thermograms is modeled by using Avrami's theory and allows an estimation of the number of crystallization germs formed. The results of optical microscopy are converted to thermograms by evaluating the average gray level of the image recorded in transmission mode as a function of temperature and calculating its temperature derivative. The shape of such optical thermograms is quite similar to that of the DSC traces but shows some peculiarities after long nucleation treatments. Atomic force microscopy was used to analyze the crystal morphology and is an additional proof of the effect of nucleation in the glassy state. The crystalline morphology observed in samples crystallized after nucleation in the glassy state is qualitatively different from that of samples nucleated above the glass transition temperature, and the number of crystals seems to be much greater than what could be expected from the crystallization kinetics.

A series of segmented poly(urethane-urea) polymers have been synthesized varying the hard segments content, based on the combination of polycaprolactone diol and aliphatic diisocyanate (Bis(4-isocyanatocyclohexyl) methane), using diamine (1,4-Butylenediamine) as the chain extender. The microstructure and properties of the material highly depend on the hard segments content (from 14 to 40%). These PUUs with hard segment content above 23% have elastomeric behaviors that allow high recoverable deformation. The chemical structure and hydrogen bonding interactions were studied using FTIR and atomic force microscopy, which revealed phase separation that was also confirmed by DSC, dynamic-mechanical, and dielectric spectroscopy.