A Bio-Physio-Psychological Investigation of Athletes' Burnout.

Purpose: Changes in biophysiological markers related to perceived burnout and self-comfort were tested in this study. Method: Forty-two student-athletes from middle and high school grades were evaluated for burnout, salivary cortisol levels, measures of arousal-related physiological markers (i.e., blood volume pulse; BVP), galvanic skin response (GSR), and respiratory rate, and self-comfort variables during the last two weeks of the season. Using self-comfort theory as its conceptual framework, we examined burnout through a conceptual model in which feeling of discomfort with the self was related to biophysiological markers affecting perceived burnout. The proposed model was tested by using a partial least squares structural equation modeling (PLS-SEM). Results: The main findings indicate that increased self-discomfort is significantly (p < .001) associated with increased salivary cortisol (ß = - 0.189) along with a significant (p = .050) decrease in GSR (ß = - 0.259). Increased salivary cortisol is significantly (p < .001) associated with increased burnout (ß = 0.242). Conclusion: The findings partially support the model and encourage further effort to capture the burnout syndrome through the integration of biological and psychological markers.

Tissue-engineered vascular grafts composed of marine collagen and PLGA fibers using pulsatile perfusion bioreactors.

Novel tubular scaffolds of marine source collagen and PLGA fibers were fabricated by freeze drying and electrospinning processes for vascular grafts. The hybrid scaffolds, composed of a porous collagen matrix and a fibrous PLGA layer, had an average pore size of 150+/-50 microm. The electrospun fibrous PLGA layer on the surface of a porous tubular collagen scaffold improved the mechanical strength of the collagen scaffolds in both the dry and wet states. Smooth muscle cells (SMCs)- and endothelial cells (ECs)-cultured collagen/PLGA scaffolds exhibited mechanical properties similar to collagen/PLGA scaffolds unseeded with cells, even after culturing for 23 days. The effect of a mechanical stimulation on the proliferation and phenotype of SMCs and ECs, cultured on collagen/PLGA scaffolds, was evaluated. The pulsatile perfusion system enhanced the SMCs and ECs proliferation. In addition, a significant cell alignment in a direction radial to the distending direction was observed in tissues exposed to radial distention, which is similar to the phenomenon of native vessel tissues in vivo. On the other hand, cells in tissues engineered in the static condition were randomly aligned. Immunochemical analyses showed that the expressions of SM alpha-actin, SM myosin heavy chain, EC von Willebrand factor, and EC nitric oxide were upregulated in tissues engineered under a mechano-active condition, compared to vessel tissues engineered in the static condition. These results indicated that the co-culturing of SMCs and ECs, using collagen/PLGA hybrid scaffolds under a pulsatile perfusion system, leads to the enhancement of vascular EC development, as well as the retention of the differentiated cell phenotype.