ABSTRACT
Cancer is one of the most life-threatening diseases worldwide. Despite the huge efforts, the failure rate of therapies remains high due to cells heterogeneity, so physiologically relevant models are strictly necessary. Bioprinting is a technology able to form highly complex 3D tissue models and enables the creation of large-scale constructs. In cancer research, Matrigel® is the most widely used matrix, but it is hardly bioprinted pure, without the use of any other bioink as reinforcement. Its complex rheological behavior makes the control with a standard bioprinting process nearly impossible. In this work, we present a customized bioprinting strategy to produce pure Matrigel® scaffolds with good shape fidelity. To this aim, we realized a custom-made volumetric dispensing system and performed printability evaluations. To determine optimal printing parameters, we analyzed fibers spreading ratio on simple serpentines. After identifying an optimal flow rate of 86.68 ± 5.77 µL/min and a printing speed of 10 mm/min, we moved forward to evaluate printing accuracy, structural integrity and other key parameters on single and multi-layer grids. Results demonstrated that Matrigel® was able to maintain its structure in both simple and complex designs, as well as in single and multilayer structures, even if it does not possess high mechanical strength. In conclusion, the use of volumetric dispensing allowed printing pure Matrigel® constructs with a certain degree of shape fidelity on both single and multiple layers.
ABSTRACT
One of the major limitations of the fiberoptic endoscopic evaluation of swallowing (FEES) is related to the challenging application of temporal measures. Among them, Whiteout (WO) is due to pharyngeal and tongue base contraction and might be used as an estimation of the pharyngeal phase duration. The aims of this study were to evaluate the inter- and intrarater reliability of WO duration and to appraise the effects of age, sex, volume, and texture of the boluses on this temporal measurement. A total of 30 healthy volunteers were recruited. According to their age, the subjects were grouped into three different age groups. Each of them underwent FEES examination with different textures (liquid, semisolid, and solid) and volumes. FEES examinations were video recorded, processed with the software Daisy Viewer 2.0, which allowed the acquisition of 25 frames per second (s) and analyzed by three different raters in order to collect data on WO duration. A total of 863 swallowing acts were video recorded. Intra- and interrater reliability of WO duration were excellent. Both volume and bolus's texture significantly affected WO duration. In particular, WO duration was significantly shorter for the liquid texture than for the semisolid and solids ones. In addition, male subjects scored significantly higher values of WO duration. Finally, WO duration was significantly higher in seniors. WO duration seems to be a reliable temporal measure during FEES examination. WO duration seems to be affected by several factors such as age, sex, volume, and consistency.
