ABSTRACT
Anatomical and functional tissue loss is one of the most debilitating problems and involves a great cost to the international health-care sector. In the field of bone tissue, the use of scaffolds to promote tissue regeneration is a topic of great interest. In this study, a combination of additive manufacturing and computational methods led to creating porous scaffolds with complex microstructure and mechanical behavior comparable to those of cancellous bone. Specifically, some representative models of triply periodic minimal surfaces (TPMSs) were 3D-printed through a stereolithographic technique using a dental resin. Schwarz primitive and gyroid surfaces were created computationally: they are characterized by a complex geometry and a high pore interconnectivity, which play a key role in the mechanism of cell proliferation. Several design parameters can be varied in these structures that can affect the performance of the scaffold: for example, the larger the wall thickness, the lower the elastic modulus and compressive strength. Morphological and mechanical analyses were performed to experimentally assess the properties of the scaffolds. The relationship between relative density and elastic modulus has been analyzed by applying different models, and a power-law equation was found suitable to describe the trend in both structures.
ABSTRACT
OBJECTIVES: Therapeutic monitoring of everolimus with chromatographic methods (HPLC) enabled effective immunosuppression while limiting the incidence of drug-related adverse events. A fluorescence polarization immunoassay (FPIA) has been recently developed for the assessment of everolimus levels. The present study was designed to evaluate FPIA performance and to compare it to HPLC. DESIGN AND METHODS: The performance of HPLC and FPIA was initially tested using drug-free whole blood spiked with different amount of everolimus concentrations and, subsequently, by analyzing 113 trough blood samples from heart transplant recipients chronically given everolimus as part of their immunosuppressive regimen. RESULTS: Inaccuracy and imprecision of both methods were below 15%. The correlation between everolimus concentrations and measured FPIA and HPLC was good, with a Pearson coefficient of 0.9118. The FPIA gave a mean overestimation of 24.3% as compared with HPLC. As additional analysis, cross-reactivity ranging from 85.4% to 138.0% was found with sirolimus, an immunosuppressant with a chemical structure close to everolimus. CONCLUSION: The FPIA demonstrated acceptable performance for therapeutic drug monitoring of everolimus, and is a viable alternative to HPLC-based methods.
