Objective: To explore the relationship between an anti epidemic mentality and post traumatic stress disorder (PTSD) among college students during the corona virus disease 2019 (COVID-19) pandemic, and to provide a scientific basis for the prevention of PTSD when college students experience sudden crisis events in the future. Methods: An online questionnaire survey was conducted among 9 399 undergraduates from Shanxi Medical University using the Posttraumatic Stress Disorder Checklist Civilian Version (PCL-C) and the public anti epidemic psychology self examination scale. Results: During the COVID-19 pandemic, the total PCL-C scores of college students were (22.74±7.78), and the positive rate of PTSD symptoms was 5.3%. The detection rates of symptom recurrence, avoidance/numbness symptoms and increased alertness symptoms were 27.0%, 16.6% and 8.6 %, respectively. The average score of avoidance/numbness symptoms in the three symptom groups was (9.21±3.39), the two items with the highest scores were repeated recall of traumatic events (1.57±0.71) and impaired concentration (1.47±0.71). Females scored higher than males on the increased alertness dimension(6.82±2.61，6.67±2.72) ( t = -6.49 ， P <0.05). In respect to PCL-C total scores and the scores of each dimension, rural areas were associated with higher scores than urban areas, and non medical students scored higher than medical students, while the scores of those who grew up with siblings were higher than only children ( P <0.05). There was a significant positive correlation between an anti epidemic mentality and total PTSD scores ( r =0.51, P <0.01). Multiple regression analysis showed that the place of origin, choice of college major, and antiepidemic mentality were predictors of PTSD symptoms ( P <0.01). Conclusion Anti epidemic mentality is associated with the occurrence of PTSD among college students.

Objective·To establish a mouse model with dormant cancer and no obvious metastasis by combining the preimmune strategy with the mVenus-p27K-cell G0 phase indicator system,the DTR-HSV/TK suicide gene system,and the Luc2-tdTomato tracer system.Methods·The KPC1199 mouse pancreatic cancer cell line was transfected with the mVenus-p27K-cell G0 phase indicator system,the DTR-HSV/TK suicide gene system,and the Luc2-tdTomato tracer system to construct a stable expression cell line,KPC1199-PDL.After being cultured in the serum-free condition,KPC1199-PDL cells were sorted into mVenus(+)cells and mVenus(-)cells by flow cytometry,and the expression of G0 phase-related genes was verified by real-time fluorescence quantitative PCR(qPCR).Sensitivity of KPC1199-PDL cells to diphtheria toxin(DTX)and ganciclovir(GCV)was evaluated by CCK-8 assay.A transsplenic portal vein-hepatic metastasis model was constructed in wild-type C57BL/6 mice to validate the function of KPC1199-PDL cells in vivo by immunofluorescence technology.The KPC1199-PDL cells were injected subcutaneously into C57BL/6 mice,followed by in situ injection of DTX and GCV to ablate subcutaneous tumors 5 d later,to obtain preimmunized mice.The transsplenic portal vein-hepatic metastasis models were constructed in these mice.Bioluminescence imaging was used to evaluate subcutaneous tumor ablation and hepatic metastasis in the mice,and immunofluorescence assay was used to detect the distribution and dormant state of tumor cells in the livers of preimmunize mice.Results·The three tool systems were stably expressed in KPC1199-PDL cells,and their proliferative ability was not affected.In the serum starving condition,some KPC1199-PDL cells expressed the mVenus protein,indicating entry into the G0 phase;the mVenus(+)cells sorted out by flow cytometry exhibited significantly higher expression of G0 phase-related genes(all P<0.05)and significantly lower expression of the proliferation-related gene compared with mVenus(-)cells(P<0.05).The CCK-8 assay demonstrated high sensitivity of KPC1199-PDL cells to DTX and GCV.In vivo experiments confirmed that KPC1199-PDL cells could be effectively traced through tdTomato protein expression,and could indicate entry into the G0 phase through mVenus protein expression.Following subcutaneous tumor implantation and drug ablation,preimmunized mice were successfully obtained.In the subsequent transsplenic portal vein-hepatic metastasis model,no metastatic signals were observed in the liver by bioluminescence imaging,but single or small clusters of G0 phase tumor cells expressing both mVenus and tdTomato,not expressing the proliferation marker Ki67,were detected in liver tissue sections by immunofluorescence analysis.Conclusions·A recognizable and traceable dormant cancer model is constructed with the combination of the preimmune mouse model of pancreatic cancer,the mVeneus-p27K-indicator system,the DTR-HSV/TK suicide gene system,and the Luc2-tdTomato tracer system.