In order to investigate in greater detail the two methods based on Hertz model for analyzing force-distance curve obtained by atomic force microscopy, we acquired the force-distance curves of Hela and MCF-7 cells by atomic force microscopy (AFM) indentation in this study. After the determination of contact point, Young's modulus in different indentation depth were calculated with two analysis methods of "two point" and "slope fitting". The results showed that the Young's modulus of Hela cell was higher than that of MCF-7 cell,which is in accordance with the F-actin distribution of the two types of cell. We found that the Young's modulus of the cells was decreased with increasing indentation depth and the curve trends by "slope fitting". This indicated that the "slope fitting" method could reduce the error caused by the miscalculation of contact point. The purpose of this study was to provide a guidance for researcher to choose an appropriate method for analyzing AFM indentation force-distance curve.
Actins ; Elastic Modulus ; HeLa Cells ; cytology ; Humans ; MCF-7 Cells ; cytology ; Microscopy, Atomic Force

Objective:To investigate the effect of blocking BRCAA1 gene expression with siRNA on the proliferation of tumor cell line MCF-7 and Rb gene expression.Methods:RNAi was employed to specifically knock down BRCAA1 expression.MCF-7 cells were transfected with complexes constructed with lipids and chemically synthesized Pre-designed anti-BRCAA1 siRNAs.The total RNA was isolated and reversely transcribed after 48 h.The expressions of BRCAA1 and Rb mRNA were determined by Real-Time PCR.Results:Compared with negative control,transfected MCF-7 cells had a 42.3% decrease in expression of BRCAA1 mRNA and an 11.1% increase in Rb mRNA expression.The inhibitory rate of MCF-7 cells proliferation was(81.6?6.1)%.Conclusion:There may be some antagonistic effect between BRCAA1 gene and Rb gene in proliferation of tumor cells,which provides a potential target for anti-tumor gene therapy.

Objective To observe the effects of different dosages of ginsenoside Rb1 preconditioning on spinal cord ischemia-reperfusion injury in rats, and the possible mechanism. Methods Sprague-Dawley rats were randomly divided into sham group (n=12), model group (n=12), and 10 mg/kg (D10, n=12), 20 mg/kg (D20, n=12), 40 mg/kg (D40, n=12) and 80 mg/kg (D80, n=12) drug groups. Spinal cord ischemia for ten minutes and reperfusion model was established, and the drug groups were injected ginsenoside Rb1 intraperitoneally in their dosages 30 minutes before modeling. They were assessed with BBB score 48 hours after reperfusion, and then were sacrificed for HE staining, TUNEL staining and immunohistochemistry staining of survivin.Results The BBB score was more in the drug groups than in the model group (P<0.05), and was the most in D40 and D80 groups. The expression of survivin was more in the drug groups than in the model group (P<0.05), and was the most in D40 and D80 groups. The apoptosis of neurons was less in the drug groups than in the model group (P<0.05), and was the least in D40 and D80 groups.Conclusion The ginsenoside Rb1 could promote the expression of survivin, inhibit apoptosis of neurons, to protect the neural function, in dose-dependent manner somehow.

【Objective】 To report the early clinical effects and surgical complications of endoscopic spinal fusion technology （Endo-LIF） in the treatment of degenerative lumbar disease. 【Methods】 The clinical data of 31 patients with degenerative lumbar spine disease treated with Endo-LIF from June 2019 to May 2021 were retrospectively analyzed. All the 31 patients underwent endoscopic spinal fusion therapy. We recorded the operation time， hospital stay duration， postoperative complications， visual analogue scale for pain （VAS）， oswestry dysfunction Index （ODI） and low back pain in the Chinese Orthopaedic Association Spine Group Surgery scoring standards before operation， immediately after operation， and the last follow-up to evaluate clinical efficacy. 【Results】 The operation time of the 31 patients was （134.80±34.98） min， the intraoperative blood loss was （100.13±18.49） mL， the hospital stay was （6.65±0.17） days， and the follow-up time was 6 to 18 （14±2.3） months. One patient had hematoma compression after surgery； he had incision made immediately to clear the hematoma and healed after bed rest. Two patients developed spinal hypertension and healed after bed rest. All the patients had no symptoms of nerve injury after operation， and the clinical symptoms were significantly relieved. We compared the perioperative VAS score and ODI index of all the patients， which were lower immediately after operation and at the last follow-up than those before the operation （P<0.05）， and the difference was statistically significant. 【Conclusion】 Endo-LIF technology has good short-term clinical effects and the advantages of milder trauma， less blood loss， and quick recovery after surgery. It is a safe and minimally invasive lumbar fusion surgery.