20 research outputs found
Composite scaffold obtained by electro-hydrodynamic technique for infection prevention and treatment in bone repair
Bone infection is a devastating condition resulting from implant or orthopaedic surgery. Therapeutic strategies are extremely complicated and may result in serious side effects or disabilities. The development of enhanced 3D scaffolds, able to promote efficient bone regeneration, combined with targeted antibiotic release to prevent bacterial colonization, is a promising tool for the successful repair of bone defects. Herein, polymeric electrospun scaffolds composed of polycaprolactone (PCL) nanofibres decorated with poly(lactic-co-glycolic acid) (PLGA) particles loaded with rifampicin were fabricated to achieve local and sustained drug release for more efficient prevention and treatment of infection. The release profile showed an initial burst of rifampicin in the first six hours, enabling complete elimination of bacteria. Sustained and long-term release was observed until the end of the experiments (28 days), facilitating a prolonged effect on the inhibition of bacterial growth, which is in agreement with the common knowledge concerning the acidic degradation of the microparticles. In addition, bactericidal effects against gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacteria were demonstrated at concentrations of released rifampicin up to 58 ppm after 24 h, with greater efficacy against S. aureus (13 ppm vs 58 ppm for E. coli). Cell morphology and cytocompatibility studies highlighted the suitability of the fabricated scaffolds to support cell growth, as well as their promising clinical application for bone regeneration combined with prevention or treatment of bacterial infection
Production, characterization and testing of antibacterial PVA membranes loaded with HA-Ag3PO4 nanoparticles, produced by SC-CO2 phase inversion
BACKGROUND: Silver-loaded hydroxyapatite nanoparticles were incorporated into poly(vinyl alcohol) (PVA) membranes obtained by supercritical CO2 (SC-CO2) assisted phase inversion. Ag3PO4 crystals of 2.2 ± 0.6 nm were dispersed in synthesized needle-like hydroxyapatite nanoparticles (20 × 65 nm) and were uniformly deposited on the internal surfaces of the PVA membranes. Operative conditions to produce membranes by SC-CO2, PVA concentration and the effect on membrane porosity and morphology were studied. RESULTS: Solutions at 20% w/w PVA produced membranes with cellular morphology and nanoporous walls, whereas 30% and 50% w/w solutions produced nanostructured membranes. Silver ions were released from PVA membranes mainly by diffusion according to the Peppas–Sahlin model. Membranes obtained at 20% w/w PVA showed a significant E. coli inhibition at an Ag concentration of 9 ppm, reaching the minimal inhibitory concentration (MIC) and improving the bactericidal activity of the nanoparticles. CONCLUSION: A concentration of Ag3PO4 crystals of about 22 ppm was calculated as being capable of completely destroying these bacteria, reaching the minimum bactericidal concentration (MBC)
Simulación de la onda de avenida por ruptura de tanque de enfriamiento
Se llevó a cabo la simulación de la ruptura del borde de un tanque de enfriamiento usando dos métodos: Uno de volúmenes finitos denominado CARPA y un algoritmo en diferencias finitas centradas. El algoritmo en volúmenes finitos CARPA utilizado con el pre y post procesador GiD mostró ser una herramienta muy poderosa en la animación de planicies de inundación, útiles en la interpretación de resultados tanto en el espacio como en el tiempo, para la protección civil, así como para definir las posibles zonas afectadas debido a fenómenos como el de la ruptura de bordo
Nondisjunction of a Single Chromosome Leads to Breakage and Activation of DNA Damage Checkpoint in G2
The resolution of chromosomes during anaphase is a key step in mitosis. Failure to disjoin chromatids compromises the fidelity of chromosome inheritance and generates aneuploidy and chromosome rearrangements, conditions linked to cancer development. Inactivation of topoisomerase II, condensin, or separase leads to gross chromosome nondisjunction. However, the fate of cells when one or a few chromosomes fail to separate has not been determined. Here, we describe a genetic system to induce mitotic progression in the presence of nondisjunction in yeast chromosome XII right arm (cXIIr), which allows the characterisation of the cellular fate of the progeny. Surprisingly, we find that the execution of karyokinesis and cytokinesis is timely and produces severing of cXIIr on or near the repetitive ribosomal gene array. Consequently, one end of the broken chromatid finishes up in each of the new daughter cells, generating a novel type of one-ended double-strand break. Importantly, both daughter cells enter a new cycle and the damage is not detected until the next G2, when cells arrest in a Rad9-dependent manner. Cytologically, we observed the accumulation of damage foci containing RPA/Rad52 proteins but failed to detect Mre11, indicating that cells attempt to repair both chromosome arms through a MRX-independent recombinational pathway. Finally, we analysed several surviving colonies arising after just one cell cycle with cXIIr nondisjunction. We found that aberrant forms of the chromosome were recovered, especially when RAD52 was deleted. Our results demonstrate that, in yeast cells, the Rad9-DNA damage checkpoint plays an important role responding to compromised genome integrity caused by mitotic nondisjunction
Effect of exploitation and exploration on the innovative as outcomes in entrepreneurial firms
[EN] The main aim of this study is to establish the effect of the Exploitation and Exploration; and the influence of these learning flows on the Innovative Outcome (IO). The Innovative Outcome refers to new products, services, processes (or improvements) that the organization has obtained as a result of an innovative process. For this purpose, a relationship model is defined, which is empirically contrasted, and can explains and predicts the cyclical dynamization of learning flows on innovative outcome in knowledge intensive firms.
The quantitative test for this model use the data from entrepreneurial firms biotechnology sector. The statistical analysis applies a method based on variance using Partial Least Squares (PLS).
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Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
Indicadores de sustentabilidad para la pesquería de curvina golfina Cynoscion othonopterus en el Alto Golfo de California
Abstract: The Upper Gulf of California and Colorado River Delta is a zone which is immersed in an ecological, economic, political and social conflict. That is because of the Totoaba Totoaba macdonaldi illegal fishing and the Vaquita Phocoena sinus potential extinction. This issue has driven to ban all the region's fisheries with the exception of the Gulf corvina Cynoscion othonopterus which is the only of the finfish species with operating license. Therefore, the main objetive was to evaluate the fishery's health condition through the Froese sustainability indicators in Upper Gulf of California during 2008, 2013, 2014 and 2015 fishing seasons. The results showed that the Gulf corvina annual production ratio showed fluctuations, highlighting in the 2012-2016 period, when the whole fishing captures with the exception of 2014, surpassed the established quota by the National Institute of Fishery (Instituto Nacional de Pesca). The size-at-maturity were: 2008= L50: 502 mm (IC= 490-514 mm), 2013= L50: 559 mm (IC= 544-576 mm), 2014= L50: 499 mm (IC= 476-518 mm), and 2015= L50: 480 mm (IC= 445-510 mm). Based on the sustainability indicators, it is demonstrated that the Gulf corvina fishery is directed towards the organisms of greater length (mega-spawners). Finally it is concluded that Gulf corvina currently shows problems of over-exploitation and therefore its exploitation is not sustainable. This suggests the need to make adjustments and updates to current management measures.Resumen: El Alto Golfo de California y Delta del Río Colorado es un área que se encuentra inmersa en un conflicto ecológico, económico, político y social debido a la pesca ilegal de totoaba Totoaba macdonaldi y la posible extinción de vaquita marina Phocoena sinus. Esto último ha provocado el cierre de todas las pesquerías en la región salvo la de curvina golfina Cynoscion othonopterus la cual es la única especie con permiso de explotación. Por lo tanto, el objetivo principal fue evaluar el estado de salud de la pesquería mediante los indicadores de sustentabilidad de Froese en el Alto Golfo de California durante las temporadas de pesca 2008, 2013, 2014 y 2015. Los resultados mostraron que la producción anual de curvina golfina presenta fluctuaciones, resaltando el periodo 2012-2016, donde las capturas totales con excepción de 2014, sobrepasaron la cuota de captura establecida por el Instituto Nacional de la Pesca. La longitud de madurez para los años estudiados fueron: 2008= L50: 502 mm (IC= 490-514 mm), 2013= L50: 559 mm (IC= 544-576 mm), 2014= L50: 499 mm (IC= 476-518 mm), y 2015= L50: 480 mm (IC= 445-510 mm). Con base en los indicadores de sustentabilidad, se demuestra que la pesquería de curvina golfina está dirigida hacia los organismos de mayor longitud (mega-reproductores). Se concluye que actualmente la curvina golfina manifiesta problemas de sobreexplotación y por ende su aprovechamiento no es sustentable. Esto sugiere la necesidad realizar ajustes y actualizaciones a las actuales medidas de manejo