Effects of Non-thermal Ultrasound on a Fibroblast Monolayer Culture: Influence of Pulse Number and Pulse Repetition Frequency.

Despite the use of therapeutic ultrasound in the treatment of soft tissue pathologies, there remains some controversy regarding its efficacy. In order to develop new treatment protocols, it is a common practice to carry out in vitro studies in cell cultures before conducting animal tests. The lack of reproducibility of the experimental results observed in the literature concerning in vitro experiments motivated us to establish a methodology for characterizing the acoustic field in culture plate wells. In this work, such acoustic fields are fully characterized in a real experimental configuration, with the transducer being placed in contact with the surface of a standard 12-well culture plate. To study the non-thermal effects of ultrasound on fibroblasts, two different treatment protocols are proposed: long pulse (200 cycles) signals, which give rise to a standing wave in the well with the presence of cavitation (ISPTP max = 19.25 W/cm2), and a short pulse (five cycles) of high acoustic pressure, which produces a number of echoes in the cavity (ISPTP = 33.1 W/cm2, with Pmax = 1.01 MPa). The influence of the acoustic intensity, the number of pulses, and the pulse repetition frequency was studied. We further analyzed the correlation of these acoustic parameters with cell viability, population, occupied surface, and cell morphology. Lytic effects when cavitation was present, as well as mechanotransduction reactions, were observed.

The Effect of PEGDE Concentration and Temperature on Physicochemical and Biological Properties of Chitosan.

Chitosan (CHT) is a polysaccharide with multiple claimed properties and outstanding biocompatibility, generally attributed to the presence of protonable amino groups rendering a cationic natural polymer. However, the effect of changes in CHT structure due to hydration is not considered in its performance. This study compares the effects on biocompatibility after drying at 25 °C and 150 °C scaffolds of chitosan, polyethylene glycol diglycidyl ether (PEGDE) crosslinked CHT (low, medium and high concentration) and glutaraldehyde (GA) crosslinked CHT. PEGDE crosslinked CHT showed a reduction in free amino groups and the amide I/II ratio, which exhaustive drying reduced further. In X-ray diffraction (DRX) analysis, PEGDE crosslinked CHT showed multiple peaks, whereas the crystallinity percentage was reduced with an increase in PEGDE concentration and thermal treatments at 150 °C. In a direct contact cell assay, high osteoblast viability was achieved at low and medium PEDGE concentrations, which was improved when the crosslinked scaffolds were thermally treated at 150 °C. This was attributed to its partial hydrophilicity, low crystallinity and low surface roughness; this in spite of the small reduction in the amount of free amino groups on the surface induced during drying at 150 °C. Furthermore, PEGDE crosslinked CHT scaffolds showed strong vinculin and integrin 1ß expression, which render them suitable for bone contact applications.

Production and characterization of supercritical CO2 dried chitosan nanoparticles as novel carrier device.

The materials produced by the supercritical CO2 drying have outstanding properties that allow the incorporation of molecules in their porous structure. In this context, dried chitosan nanoparticles including ß-lactoglobulin were obtained. First, the nanoparticles in water suspension were produced by ionotropic gelation incorporating the protein with high loading efficiency. Later, solvent exchange and CO2 supercritical drying procedures were performed. The physicochemical characteristics and structural properties were determined, demonstrating a stable porous structure in the dried materials and corroborating the presence of the protein after the drying. The CO2 supercritical dried chitosan nanoparticles can be effectively resuspended in acidic aqueous medium remaining in the nanoscale with minimum effect on the loading parameters. The release of the ß-lactoglobulin was highly influenced by the pH, reaching around 40% under acidic conditions in ten hours. The obtained results demonstrate the possibility to apply these chitosan materials as a controlled release material.

Signal conditioning for differential temperature measurement with thermistors using a generalized impedance converter.

In this article a differential temperature-to-time converter is presented using two thermistors in a generalized impedance converter, polarized in direct current. The voltage drop in one of the thermistors depends on the differential temperature at which both thermistors are exposed. Such voltage drop is compared to a signal which changes exponentially by obtaining a time interval which depends on the differential temperature. The results of the experimental tests support the theoretical analysis performed and at the same time offer a new possibility of application of the generalized impedance converter as a signal conditioning circuit.

Comparative study on the properties of acrylic bone cements prepared with either aliphatic or aromatic functionalized methacrylates.

Bone cements prepared with methacrylic acid (MAA) and diethyl amino ethyl methacrylate (DEAEM) were compared with formulations employing 4-methacryloyloxybenzoic acid (MBA) and 4-diethyaminobenzyl methacrylate (DEABM) as comonomer. The influence of these new aromatic monomers on various physicochemical, setting and mechanical properties was assessed. Surface characterization demonstrated that bone cements prepared with any of the functionalized monomers exhibited increasing hydrophilicity with monomer concentration and that the aromatic monomers provided more hydrophilic cements than their aliphatic counterparts for low concentrations of the functional monomer. It was also found that bone cements prepared with high amounts of the acidic aliphatic monomer provided the highest exotherm of reaction and their setting times were shorter than MBA based cements. On the other hand, DEABM containing bone cements exhibited shorter setting times than DEAEM formulations and slightly higher peak temperatures. In general, it was found that the glass transition temperature increased with the presence of acidic comonomer and decreased when alkaline comonomers were present, especially aliphatic ones. When aromatic methacrylates were used at 0.05 molar fraction, the highest tensile and compressive strength were achieved i.e. 46 and 118 MPa for MBA and 51 and 108 MPa for DEABM formulations. A further increase in the aromatic monomer concentration led to cements of low mechanical properties due to solubility problems as revealed by SEM.

Circulación silenciosa de poliovirus demostrada por interferencia a los enterovirus no polio / Silent circulation of poliovirus demonstrated by interference against non-polio enterovirus

Se obtuvieron muestras de heces semanalmente, en niños menores de 3 años para aislar los poliovirus y enterovirus no polio, con el objetivo de incrementar el conocimiento de las circulaciones de los derivados de la vacuna durante las campañas masivas. Los esquemas de vacunación continua permiten la circulación de esos virus durante grandes períodos de tiempo. En los niños se demostró una interferencia de los enterovirus no polio por los poliovirus vacunales. Sin embargo, mientras los bajos porcentajes de enterovirus no polio no mostraron diferencias significativas, sí se encontró en los altos porcentajes de poliovirus vacunales aislados en niños menores de 1 año en relación con los de 1 y 2 años. Basados en esa contradicción, se estimó la circulación silenciosa de los poliovirus por cálculos matemáticos. Con los poliovirus estimados se permitió obtener las curvas simuladas. Posteriormente, en otra investigación se confirmaron los resultados por métodos inmunológicos

Circulación silenciosa de poliovirus demostrada por interferencia a los enterovirus no polio / Silent circulation of poliovirus demonstrated by interference against non-polio enterovirus

Se obtuvieron muestras de heces semanalmente, en niños menores de 3 años para aislar los poliovirus y enterovirus no polio, con el objetivo de incrementar el conocimiento de las circulaciones de los derivados de la vacuna durante las campañas masivas. Los esquemas de vacunación continua permiten la circulación de esos virus durante grandes períodos de tiempo. En los niños se demostró una interferencia de los enterovirus no polio por los poliovirus vacunales. Sin embargo, mientras los bajos porcentajes de enterovirus no polio no mostraron diferencias significativas, sí se encontró en los altos porcentajes de poliovirus vacunales aislados en niños menores de 1 año en relación con los de 1 y 2 años. Basados en esa contradicción, se estimó la circulación silenciosa de los poliovirus por cálculos matemáticos. Con los poliovirus estimados se permitió obtener las curvas simuladas. Posteriormente, en otra investigación se confirmaron los resultados por métodos inmunológicos(AU)

Injectable acrylic bone cements for vertebroplasty with improved properties.

Currently commercially available acrylic bone cements lack adequate radiopacity and viscosity when they are used in percutaneous vertebroplasty (PVP). In this work improved formulations of radiopaque and injectable poly(methyl methacrylate) bone cements were prepared with different amounts (10-50 wt.%) of BaTiO3 or SrTiO3 particles as the radiopaque agent. Two sets of cements were prepared by using untreated or silanated radiopaque particles, respectively. The influence of the content and nature of the radiopaque agent as well as its silanation with 3-(trimethoxysilyl) propyl methacrylate (gamma-MPS), on the curing parameters, residual monomer content, radiopacity, mechanical properties, and injectability of the resulting materials, was examined. Doughing and setting times, maximum temperature, and compressive strength of all formulations fulfilled the requirements of standard specifications, with values of peak temperature in the range 57-72 degrees C and those of compressive strength between 114 and 135 MPa. Formulations containing at least 20 wt.% BaTiO3 or SrTiO3 had radiopacities equal to or greater than that corresponding to 2 mm of Al as required for surgical plastics. Injectability of any of the formulations provided 75-80 wt.% of the total mass manually injected through a conventional biopsy needle 4 min after mixing. Silanation of the BaTiO3 or SrTiO3 particles led to formulations with improved mechanical properties and injectability compared to those obtained with the untreated fillers.

[Silent circulation of poliovirus demonstrated by interference against non-polio enterovirus]. / Circulación silenciosa de poliovirus demostrada por interferencia a los enterovirus no polio.

Fecal samples were weekly obtained from children under 3 years of age to isolate non-polio poliovirus and enterovirus and to expand the knowledge on circulation of vaccine-derived viruses during mass campaigns. The steady vaccination schedules allow the circulation of these viruses for long periods of time. The interference of non-polio enterovirus by vaccine poliovirus was demonstrated in children. However, the low percentages of non-polio enterovirus did not show significant differences whereas these differences were significant in high percentages of vaccine poliovirus isolated in children under one year-old in comparison with those of 1 and 2 years of age. Based on this contradiction, mathematical calculations estimated the silent circulation of poliovirus that in turn made it possible to draw simulated curves. The results were later confirmed in another research work by using immunological methods.