Polyurethane-based bioadhesive synthesized from polyols derived from castor oil (Ricinus communis) and low concentration of chitosan

[EN] Polyurethane-based bioadhesive was synthesized with polyols derived from castor oil (chemically modified and unmodified) and hexamethylene diisocyanate with chitosan addition as a bioactive filler. The objective was to evaluate the effect of type of polyols with the incorporation of low-concentrations of chitosan on the mechanical and biological properties of the polymer to obtain suitable materials in the design of biomaterials. The results showed that increasing physical crosslinking increased the mechanical and adhesive properties. An in vitro cytotoxic test of polyurethanes showed cellular viability. The biocompatibility of the polyurethanes favors the adhesion of L929 cells at 6, 24, and 48 h. The polyurethanes showed bacterial inhibition depending on the polyol and percentage of chitosan. The antibacterial effect of the polyurethanes for Escherichia coli decreased 60-90% after 24 h. The mechanical and adhesive properties together with biological response in this research suggested these polyurethanes as external application tissue bioadhesives.This work was supported by the Universidad de La Sabana under grant number ING-176-2016 and by Colciencias under scholarship grant 617-2-2014. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. J.A.G.T. and A.V.L. acknowledge the support of the Spanish Ministry of Economy and Competitiveness (MINECO) through project DPI2015-65401-C3-2-R (including FEDER financial support). Finally, the authors thank the Universitat Politecnica de Valencia for assistance and advice with the equipment.Uscátegui, YL.; Arevalo-Alquichire, SJ.; Gómez-Tejedor, J.; Vallés Lluch, A.; Diaz, LE.; Valero, MF. (2017). Polyurethane-based bioadhesive synthesized from polyols derived from castor oil (Ricinus communis) and low concentration of chitosan. Journal of Materials Research. 32(19):3699-3711. https://doi.org/10.1557/jmr.2017.371S36993711321

Hydrolytic stability and biocompatibility on smooth muscle cells of polyethylene glycol-polycaprolactone-based polyurethanes

[EN] Interactions between smooth muscle cells (SMCs) and biomaterials must not result in phenotype changes as this may generate uncontrolled multiplication processes and occlusions in vascular grafts. The aim of this study was to relate the hydrolytic stability and biocompatibility of polyurethanes (PUs) on SMCs. A higher polycaprolactone (PCL) concentration was found to improve the hydrolytic stability of the material and the adhesion of SMCs. A material with 5% polyethylene glycol, 90% PCL, and 5% pentaerythritol presented high cell viability and adhesion, suggesting a contractile phenotype in SMCs depending on the morphology. Nevertheless, all PUs retained their elastic modulus over 120 days, similar to the collagen of native arteries (similar to 10 MPa). Furthermore, aortic SMCs did not present toxicity (viability over 80%) and demonstrated adherence without any abnormal cell multiplication processes, which is ideal for the function to be fulfiled in situ in the vascular grafts.The research and publication were supported by the Universidad de La Sabana (ING-205-2018) and the Minister of Science, Technology, and Innovation of the Republic of Colombia, MINCIENCAS (Contract number 80740-186-2019). M. M-G. would like to thank the Universidad de La Sabana for the scholarship for her master's studies. S. A-A. would like to thank MINCIENCIAS for the doctoral training scholarship (Grant 727-2015). The authors are thankful to Professor Ericsson Coy Barrera and his staff at Nueva Granada Military University for the access to the VarioskanT LUX multimode microplate reader. J. A. S. acknowledges the financial support by MINECO through FIS2017-83295-P, MAT2015-71070-REDC, MAT2016-75586-C4-1/2/3-P and the Ramon y Cajal Fellowship (RYC-201517482). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund.Morales-Gonzalez, M.; Arévalo-Alquichire, S.; Diaz, LE.; Sans-Tresserras, JÁ.; Vilariño, G.; Gómez-Tejedor, J.; Valero, MF. (2020). Hydrolytic stability and biocompatibility on smooth muscle cells of polyethylene glycol-polycaprolactone-based polyurethanes. Journal of Materials Research. 35(23-24):3276-3285. https://doi.org/10.1557/jmr.2020.303S327632853523-24Benrashid, E., McCoy, C. C., Youngwirth, L. M., Kim, J., Manson, R. J., Otto, J. C., & Lawson, J. H. (2016). Tissue engineered vascular grafts: Origins, development, and current strategies for clinical application. Methods, 99, 13-19. doi:10.1016/j.ymeth.2015.07.014Asadpour, S., Ai, J., Davoudi, P., Ghorbani, M., Jalali Monfared, M., & Ghanbari, H. (2018). 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Journal of Materials Research, 32(19), 3699-3711. doi:10.1557/jmr.2017.371Horakova, J., Mikes, P., Saman, A., Jencova, V., Klapstova, A., Svarcova, T., … Lukas, D. (2018). The effect of ethylene oxide sterilization on electrospun vascular grafts made from biodegradable polyesters. Materials Science and Engineering: C, 92, 132-142. doi:10.1016/j.msec.2018.06.041Liu, X., Xia, Y., Liu, L., Zhang, D., & Hou, Z. (2018). Synthesis of a novel biomedical poly(ester urethane) based on aliphatic uniform-size diisocyanate and the blood compatibility of PEG-grafted surfaces. Journal of Biomaterials Applications, 32(10), 1329-1342. doi:10.1177/0885328218763912Uscátegui, Y., Díaz, L., Gómez-Tejedor, J., Vallés-Lluch, A., Vilariño-Feltrer, G., Serrano, M., & Valero, M. (2019). Candidate Polyurethanes Based on Castor Oil (Ricinus communis), with Polycaprolactone Diol and Chitosan Additions, for Use in Biomedical Applications. 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Polyurethanes from modified castor oil and chitosan. Synthesis, characterization, in vitro degradation, and cytotoxicity

[EN] Polyurethanes (PUs) from castor oil (CO), modified CO (MCO) by transesterification reaction, isophorone diisocyanate (IPDI) in an NCO/OH ratio equal to 1, and chitosan (CS) were synthesized to assess their potential as biomaterials. PUs were characterized by Fourier transform infrared spectroscopy, hydroxyl value (ASTM D1957), thermogravimetric analysis, Shore A hardness (ASTM D2240), and scanning electronic microscopy (SEM). Also, contact angle, water retention and in vitro degradation in PBS, and cell viability on fibroblast were performed. The hydroxyl value confirms CO modification, and IR analysis confirms urethane bond formation. The thermal assay does not show new degradation stages and polyol with a high functionality had better hardness performance due to the increase in cross-linking. The micrograph shows micro-phase separation of both polymers. The contact angle shows the hydrophobic surface with an angle over 65°, and the CS and polyol type do not affect swelling and in vitro degradation due to phase separation between both polymers. The cell viability was over 70% in all cases, and solid polymers and degradation products involve non-cytotoxic effects on the samples. The results suggest a potential for these formulations in the biomedical field.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Universidad de La Sabana under Grant number ING-160-2015. Also, Jose A. Gomez-Tejedor and Ana Valles-Lluch acknowledge the support of the Spanish Ministry of Economy and Competitiveness (MINECO) through the project DPI2015-65401-C3-2-R (including the FEDER financial support).Arévalo-Alquichire, S.; Ramírez, C.; Andrade, L.; Uscategui, Y.; Diaz, LE.; Gómez-Tejedor, JA.; Vallés Lluch, A.... (2018). Polyurethanes from modified castor oil and chitosan. Synthesis, characterization, in vitro degradation, and cytotoxicity. Journal of Elastomers and Plastics. 50(5):419-434. https://doi.org/10.1177/0095244317729578S41943450

Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films

[EN] Polyurethanes (PUs) from Polyethylene glycol (PEG) and polycaprolactone diol (PCL) and a crosslinker, Pentaerythritol (PE), were synthetized with isophorone diisocyanate (IPDI). In this study, we investigated the effect of polyol and crosslinker composition on phase separation and thermo-mechanical properties. The properties were studied through dynamic mechanical analysis, X-ray scattering, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed changes in PUs properties, microphase structure, and separation due to the composition of polyol/crosslinker blend. So, the largest concentration of PE produced multimodal loss factor patterns, indicating segment segregation while PUs with a PEG/PCL = 1 displayed a monomodal loss factor pattern, indicating a homogeneously distributed microphase separation. Additionally, the increase of the PEG concentration enhanced the damping capacity. On the other hand, agglomeration and thread-like structures of hard segments (HS) were observed through AFM. Finally, the thermal behavior of PUs was affected by chemical composition. Lower concentration of PE reduced the crosslinking; hence, the temperature with the maximum degradation rate.This work was supported by: Universidad de La Sabana (Grant number ING-176-2016); COLCIENCIAS, today Minister of Science, Technology and Innovation of the republic of Colombia, (Grant number 808-2018); Fondo Francisco Jose de Caldas (Contract number CT22-2017). CIBER-BBN is an initiative funded by the VI National R&D & I Plan 2008-2011, "IniciativaIngenio 2010", Consolider Program. CIBER actions are financed by the "Instituto de Salud Carlos III" with assistance from the European Regional Development Fund. DocumentArevalo-Alquichire, S.; Morales-Gonzalez, M.; Navas-Gomez, K.; Diaz, LE.; Gómez-Tejedor, J.; Serrano, M.; Valero, MF. (2020). Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films. Polymers. 12(3):1-13. https://doi.org/10.3390/polym12030666S113123Kim, H.-N., Lee, D.-W., Ryu, H., Song, G.-S., & Lee, D.-S. (2019). Preparation and Characterization of Isosorbide-Based Self-Healable Polyurethane Elastomers with Thermally Reversible Bonds. Molecules, 24(6), 1061. doi:10.3390/molecules24061061Arévalo-Alquichire, S., Morales-Gonzalez, M., Diaz, L., & Valero, M. (2018). Surface Response Methodology-Based Mixture Design to Study the Influence of Polyol Blend Composition on Polyurethanes’ Properties. Molecules, 23(8), 1942. doi:10.3390/molecules23081942Brzeska, J., Elert, A., Morawska, M., Sikorska, W., Kowalczuk, M., & Rutkowska, M. (2018). Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties. Polymers, 10(8), 826. doi:10.3390/polym10080826Klinedinst, D. B., Yilgör, I., Yilgör, E., Zhang, M., & Wilkes, G. L. (2012). The effect of varying soft and hard segment length on the structure–property relationships of segmented polyurethanes based on a linear symmetric diisocyanate, 1,4-butanediol and PTMO soft segments. Polymer, 53(23), 5358-5366. doi:10.1016/j.polymer.2012.08.005Guazzini, T., Bronco, S., Carignani, E., & Pizzanelli, S. (2019). Tunable ionization degree in cationic polyurethanes and effects on phase separation. European Polymer Journal, 114, 298-307. doi:10.1016/j.eurpolymj.2019.02.023Ordon, K., Szlachta, M., Szatkowski, P., & Pielichowska, K. (2019). Examining the effect of starch and hydroxyapatite crosslinking on the thermal properties of polyurethane-based biomaterials. Thermochimica Acta, 682, 178414. doi:10.1016/j.tca.2019.178414Mondal, S., & Martin, D. (2012). Hydrolytic degradation of segmented polyurethane copolymers for biomedical applications. Polymer Degradation and Stability, 97(8), 1553-1561. doi:10.1016/j.polymdegradstab.2012.04.008Wang, C., Xie, J., Xiao, X., Chen, S., & Wang, Y. (2019). Development of Nontoxic Biodegradable Polyurethanes Based on Polyhydroxyalkanoate and L-lysine Diisocyanate with Improved Mechanical Properties as New Elastomers Scaffolds. Polymers, 11(12), 1927. doi:10.3390/polym11121927Li, J.-W., Lee, H.-T., Tsai, H.-A., Suen, M.-C., & Chiu, C.-W. (2018). Synthesis and Properties of Novel Polyurethanes Containing Long-Segment Fluorinated Chain Extenders. Polymers, 10(11), 1292. doi:10.3390/polym10111292Amrollahi, M., Sadeghi, G. M. M., & Kashcooli, Y. (2011). Investigation of novel polyurethane elastomeric networks based on polybutadiene-ol/polypropyleneoxide mixture and their structure–properties relationship. Materials & Design, 32(7), 3933-3941. doi:10.1016/j.matdes.2011.02.039Tan, C., Tirri, T., & Wilen, C.-E. (2017). Investigation on the Influence of Chain Extenders on the Performance of One-Component Moisture-Curable Polyurethane Adhesives. Polymers, 9(12), 184. doi:10.3390/polym9050184Imre, B., Gojzewski, H., Check, C., Chartoff, R., & Vancso, G. J. (2017). Properties and Phase Structure of Polycaprolactone-Based Segmented Polyurethanes with Varying Hard and Soft Segments: Effects of Processing Conditions. Macromolecular Chemistry and Physics, 219(2), 1700214. doi:10.1002/macp.201700214Mondal, S., & Hu, J. L. (2006). Structural characterization and mass transfer properties of nonporous segmented polyurethane membrane: Influence of hydrophilic and carboxylic group. Journal of Membrane Science, 274(1-2), 219-226. doi:10.1016/j.memsci.2005.08.016Coleman, M. M., Pehlert, G. J., & Painter, P. C. (1996). Functional Group Accessibility in Hydrogen Bonded Polymer Blends. Macromolecules, 29(21), 6820-6831. doi:10.1021/ma9604045Lei, W., Zhou, X., Fang, C., Li, Y., Song, Y., Wang, C., & Huang, Z. (2019). New approach to recycle office waste paper: Reinforcement for polyurethane with nano cellulose crystals extracted from waste paper. Waste Management, 95, 59-69. doi:10.1016/j.wasman.2019.06.003Lei, W., Fang, C., Zhou, X., Li, Y., & Pu, M. (2018). Polyurethane elastomer composites reinforced with waste natural cellulosic fibers from office paper in thermal properties. Carbohydrate Polymers, 197, 385-394. doi:10.1016/j.carbpol.2018.06.036Ma, C., Chen, E., Sun, T., Shi, S., & Fang, Q. (2012). Preparation and characterization of tetrapod-shaped ZnO whisker filled polyurethane cross-linked epoxy/polyurethane damping composites. Journal of Reinforced Plastics and Composites, 31(22), 1564-1575. doi:10.1177/0731684412446856HUDA, M., DRZAL, L., MOHANTY, A., & MISRA, M. (2006). Chopped glass and recycled newspaper as reinforcement fibers in injection molded poly(lactic acid) (PLA) composites: A comparative study. Composites Science and Technology, 66(11-12), 1813-1824. doi:10.1016/j.compscitech.2005.10.015Li, T., Zheng, T., Han, J., Liu, Z., Guo, Z.-X., Zhuang, Z., … Guo, B.-H. (2019). Effects of Diisocyanate Structure and Disulfide Chain Extender on Hard Segmental Packing and Self-Healing Property of Polyurea Elastomers. Polymers, 11(5), 838. doi:10.3390/polym11050838Cao, Q., & Liu, P. (2007). Crystalline-amorphous phase transition of hyperbranched polyurethane phase change materials for energy storage. Journal of Materials Science, 42(14), 5661-5665. doi:10.1007/s10853-006-0884-zPang, G. K. ., Baba-Kishi, K. ., & Patel, A. (2000). Topographic and phase-contrast imaging in atomic force microscopy. Ultramicroscopy, 81(2), 35-40. doi:10.1016/s0304-3991(99)00164-3Lu, X., Xu, M., Sheng, Y., Li, Z., & Li, H. (2019). Preparation of polyurethanes with broad damping temperature range and self-healing properties. 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NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array

NectarCAM is a camera proposed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog to Digital converter. The camera will be equipped with 265 7-photomultiplier modules, covering a field of view of 8 degrees. Each module includes the photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and Ethernet transceiver. The recorded events last between a few nanoseconds and tens of nanoseconds. The camera trigger will be flexible so as to minimize the read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data rate of more than 4 kHz with less than 5\% dead time. The camera concept, the design and tests of the various subcomponents and results of thermal and electrical prototypes are presented. The design includes the mechanical structure, cooling of the electronics, read-out, clock distribution, slow control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

Temperate phages both mediate and drive adaptive evolution in pathogen biofilms

Temperate phages drive genomic diversification in bacterial pathogens. Phage-derived sequences are more common in pathogenic than non-pathogenic taxa, and are associated with changes in pathogen virulence. High abundance and mobilisation of temperate phages within hosts suggests that temperate phages could promote within-host evolution of bacterial pathogens. However,their role in pathogen evolution has not been experimentally tested. We experimentally evolved replicate populations of Pseudomonas aeruginosa with or without a community of three temperate phages active in cystic fibrosis (CF) lung infections, including the transposable phage, ɸ4, which is closely related to phage D3112. Populations grew as free-floating biofilms in artificial sputum medium, mimicking sputum of CF lungs where P. aeruginosa is an important pathogen and undergoes evolutionary adaptation and diversification during chronic infection. While bacterial populations adapted to the biofilm environment in both treatments, population genomic analysis revealed that phages altered both the trajectory and mode of evolution. Populations evolving with phages exhibited a greater degree of parallel evolution and faster selective sweeps than populations without phages. Phage ɸ4, integrated randomly into the bacterial chromosome but integrations into motility-associated genes and regulators of quorum sensing systems essential for virulence were selected in parallel, strongly suggesting that these insertional inactivation mutations were adaptive. Temperate phages, and in particular transposable phages, are therefore likely to facilitate adaptive evolution of bacterial pathogens within hosts

Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate´s phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.J.T.S. holds a research contract from the Fundación para la Formación e Investigación de los Profesionales de la Salud de Extremadura (FundeSalud), Instituto de Salud Carlos III. M.F.R. holds a clinical research contract “Juan Rodés” (JR14/00036) from the Spanish Ministry of Economy and Competitiveness, Instituto de Salud Carlos III

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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