Bioactivity of dexamethasone-releasing coatings on polymer/magnesium composites.

We developed biodegradable polymeric coatings loaded with increasing amounts of dexamethasone on composites based on polylactic acid and Mg particles for bone repair. Incorporation of Mg particles into the polymeric matrix improves the compressive behaviour of the polymer. Mg-containing composites release Mg2+ ions into the culture medium and improve mesenchymal stem cell (MSC) viability, enhance their osteogenic potential and promote the release of angiogenic factors. Dexamethasone-loaded coatings deposited on composites delay Mg2+ ion dissolution while releasing controlled amounts of the drug, which are highly dependent on initial payload. Release kinetic of dexamethasone from the coatings exhibits a fast initial release of the drug followed by a slower secondary release. Bioactivity of the released dexamethasone was explored by monitoring dose-dependent responses of MSCs and macrophages. Biological effects exerted by the released drug are similar to those observed in cells treated with solutions of the glucocorticoid, indicating that the method employed for inclusion of dexamethasone into the coatings does not impair its bioactive behaviour. Culturing MSCs on dexamethasone-releasing coatings enhances extracellular matrix production and initial induction to osteogenic commitment as a function of drug payload. Dexamethasone incorporated into the coatings presents anti-inflammatory activity, as shown by the decrease in the production of cytokines and angiogenic factors by macrophages and MSCs. Deposition of dexamethasone-releasing coatings on polymer/Mg composites appears to be a promising approach to delay composite degradation at the early stage of implantation and may be useful to attenuate inflammation and adverse foreign body reactions.

Evaluation of immunoassays as an alternative for the rapid determination of pesticides in wine and grape samples.

The main objective of this paper is to address the performance of immunochemical assays for the detection of the residues of three pesticides [atrazine, bromopropylate, and 2,4,6-trichlorophenol (TCP)] in real winery samples, such as wine, grapes, and grape juice. Different approaches have been evaluated to minimize interferences from the matrixes, and suitable working protocols have been established in order to achieve the necessary LODs, accuracy, and precision for real samples. A simple dilution of the sample proved to be sufficient for the determination of atrazine and bromopropylate in red and white wine and grape juice at the required levels of concentration. However, for TCP, an SPE procedure has been optimized using amino cartridges. The recoveries were above 85% in all cases, and the LOD values were below the parts per billion level, except for bromopropylate, which ranged between 2 and 50 microg/L, depending on the matrix. The grape matrix effect could be resolved by a simple extraction with methanol. Complete recoveries were obtained, and the final measurement procedures were able to determine selected pesticides below their maximum residue levels. The newly developed methods have been compared with standard chromatographic methods.

Modelling spoilage of fresh turbot and evaluation of a time-temperature integrator (TTI) label under fluctuating temperature.

Kinetic models were developed to predict the microbial spoilage and the sensory quality of fresh fish and to evaluate the efficiency of a commercial time-temperature integrator (TTI) label, Fresh Check(R), to monitor shelf life. Farmed turbot (Psetta maxima) samples were packaged in PVC film and stored at 0, 5, 10 and 15 degrees C. Microbial growth and sensory attributes were monitored at regular time intervals. The response of the Fresh Check device was measured at the same temperatures during the storage period. The sensory perception was quantified according to a global sensory indicator obtained by principal component analysis as well as to the Quality Index Method, QIM, as described by Rahman and Olley [Rahman, H.A., Olley, J., 1984. Assessment of sensory techniques for quality assessment of Australian fish. CSIRO Tasmanian Regional Laboratory. Occasional paper n. 8. Available from the Australian Maritime College library. Newnham. Tasmania]. Both methods were found equally valid to monitor the loss of sensory quality. The maximum specific growth rate of spoilage bacteria, the rate of change of the sensory indicators and the rate of change of the colour measurements of the TTI label were modelled as a function of temperature. The temperature had a similar effect on the bacteria, sensory and Fresh Check kinetics. At the time of sensory rejection, the bacterial load was ca. 10(5)-10(6) cfu/g. The end of shelf life indicated by the Fresh Check label was close to the sensory rejection time. The performance of the models was validated under fluctuating temperature conditions by comparing the predicted and measured values for all microbial, sensory and TTI responses. The models have been implemented in a Visual Basic add-in for Excel called "Fish Shelf Life Prediction (FSLP)". This program predicts sensory acceptability and growth of spoilage bacteria in fish and the response of the TTI at constant and fluctuating temperature conditions. The program is freely available at http://www.azti.es/muestracontenido.asp?idcontenido=980&content=15&nodo1=30&nodo2=0.