Objective:To study the expression of miRNA-7 in B lymphocytes of primary Sj?gren's syndrome (pSS) and its relationship with phosphatase andtensin homolog deleted (PETN) and disease activity.Methods:Twenty newly diagnosed outpatient and inpatient pSS patients were used as case group collected from January 2017 to December 2019 of Qinghai Provincial People's Hospital. Twentyhealthy persons were used as the control group. Disease-related indicators of the case group were collected. Quantitative polymerase chain reaction (RT-qPCR)was used to detect miRNA-7 and PETN mRNA expression in B lymphocytes of the two groups and the consistency between miRNA-7 expression in the plasma and B lymphocytes of the case group was analyzed. Western Blotting method was used to detect the PETN protein in B lymphocytes of the two groups. Correlation analysis was used to analyze the relationship between miRNA-7 expression in B lymphocytes and disease activity in the case group. Linear regression analysis was performed between miRNA-7 and PETN mRNA.Results:The expression of miRNA-7 (0.53±0.17) in the B cells increased and the expression of PTEN mRNA (0.88± 0.24) and protein (0.51±0.12) in the case group were reduced compared with that of miRNA-7(0.39±0.11), PTEN mRNA(2.32±0.30) and protein(1.03±0.21) of the control group. The above differences were statistically significant ( t=2.990, P<0.05; t=16.98, P<0.05; t=8.41, P<0.05). Linear regression showedthat PTEN miRNAwas negatively correlated with miRNA-7 ( b=-0.78, P<0.01), the expression of miRNA-7 in the case group was positively related with EULAR Sj?gren′s syndrome Disease Activity Index (ESSDAI), IgG, IgA, anti-SSB and was negatively correlated with C4 and WBC. Conclusion:There is a certain relationship between miRNA-7 and disease activity. MiRNA-7 may participate in the pathogenesis of pSS byregulating PETN in B cells of pSS. MiRNA-7 has certain clinical value for disease activity evaluation.

Objective To conduct dynamic impact failure test of rabbit single vertebra, and make comparison with the static compression experiment, so as to study damage mechanism of the vertebral body under the axial impact. Methods The voltage waveform diagram of the force sensor and the detailed process of the vertebral impact were obtained by the oscilloscope and high-speed photography through the drop hammer dynamic impact experimental device. Results The average static load of the thoracic and lumbar vertebra were 910 N and 947 N, respectively; the average dynamic load of the thoracic and lumbar vertebra were 1 196 N and 1 026 N, respectively; the average thoracic and lumbar dynamic load coefficients were 1.37 and 1.08; under static load, the average stress of the thoracic and lumbar vertebra was 15.28 MPa and 12.51 MPa, respectively; under dynamic load, the average stress of the thoracic and lumbar vertebra was 20.03 MPa and 13.56 MPa; during dynamic impact, the mean longitudinal strain and transverse strain was -0.3 and -0.005 (compression); under dynamic conditions, the destruction energy of vertebrae increased from 0 J to 4.4 J. Conclusions Under dynamic and static experimental conditions, the dynamic load of the same vertebral body was greater than that of the static load; the average dynamic load coefficient of the thoracic vertebra was larger than that of the lumbar vertebra; the equivalent stress of the thoracic vertebra was greater than that of the lumbar vertebra; the axial strain of vertebra under impact was greater than the transverse strain; energy growth of the vertebral body presented a slow at first and then a rapid changing process. The research findings can provide some guidance for prevention and rehabilitation of human vertebral body injury in clinic.