Recent studies have shown the importance of cell–substrate interaction on neurone outgrowth, where the Young’s modulus of the matrix plays a crucial role on the neurite length, migration, proliferation, and morphology of neurones. In the present study, PC12 cells were selected as the representative neurone to be cultured on hydrogel substrates with different stiffness to explore the effect of substrate stiffness on the neurone outgrowth. By adjusting the concentration of gelatin methacryloyl (GelMA), the hydrogel substrates with the variation of stiffnesses (indicated by Young’s modulus) from approximately 3–180 KPa were prepared. It is found that the stiffness of GelMA substrates influences neuronal outgrowth, including cell viability, adhesion, spreading, and average neurite length. Our results show a critical range of substrate’s Young’s modulus that support PC12 outgrowth, and modulate the cell characteristics and morphology. The present study provides an insight into the relationship between the stiffness of GelMA hydrogel substrates and PC12 cell outgrowth, and helps the design and optimization of tissue engineering scaffolds for nerve regeneration.

Background: We aimed to compare the accuracy of individuals’ wrist and forehead temperatures with their tympanic temperature under different circumstances. Methods: We performed a prospective observational study in a real-life population in Ningbo First Hospital in China. We consecutively recorded individuals’ wrist and forehead temperatures in Celsius (°C) using a noncontact infrared thermometer (NCIT). We also measured individuals’ tympanic temperature using a tympanic thermometer (IRTT) and defined fever as a tympanic temperature of ≥37.3 °C. Results: We enrolled 528 participants, including 261 indoor and 267 outdoor participants. We grouped the outdoor participants into four groups according to their means of transportation to the hospital: by foot, by bicycle/electric vehicle, by car, or as a passenger in a car. Under different circumstances, the mean difference in the forehead measurement ranged from -1.72 to -0.56 °C across groups, and that in the wrist measurement ranged from -0.96 to -0.61°C. Both measurements had high fever screening abilities in indoor patients. (Wrist: AUC 0.790; 95% CI: 0.725-0.854, P<0.001; forehead: AUC 0.816; 95% CI: 0.757-0.876, P <0.001). The cut-off value of the wrist measurement for detecting a tympanic temperature of ≥37.3 °C was 36.2 °C, with 86.4% sensitivity and 67.0% specificity, and the best threshold for the forehead measurement was 36.2 °C, with 93.2% sensitivity and 60.0% specificity. Conclusion: Wrist measurements are more stable than forehead measurements under different circumstances. Both measurements have favorable fever screening abilities in indoor patients. The cut-off values were both 36.2 °C.

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