PURPOSE: Intertrochanteric fractures undergoing proximal femoral nail antirotation (PFNA) surgery are associated with significant hidden blood loss. This study aimed to explore whether intramedullary administration of tranexamic acid (TXA) can reduce bleeding in PFNA surgery for intertrochanteric fractures in elderly individuals. METHODS: A randomized controlled trial was conducted from January 2019 to December 2022. Patients aged over 60 years with intertrochanteric fractures who underwent intramedullary fixation surgery with PFNA were eligible for inclusion and grouped according to random numbers. A total of 249 patients were initially enrolled, of which 83 were randomly allocated to the TXA group and 82 were allocated to the saline group. The TXA group received intramedullary perfusion of TXA after the bone marrow was reamed. The primary outcomes were total peri-operative blood loss and post-operative transfusion rate. The occurrence of adverse events was also recorded. Continuous data was analyzed by unpaired t-test or Mann-Whitney U test, and categorical data was analyzed by Pearson Chi-square test. RESULTS: The total peri-operative blood loss (mL) in the TXA group was significantly lower than that in the saline group (577.23 ± 358.02 vs. 716.89 ± 420.30, p = 0.031). The post-operative transfusion rate was 30.67% in the TXA group and 47.95% in the saline group (p = 0.031). The extent of post-operative deep venous thrombosis and the 3-month mortality rate were similar between the 2 groups. CONCLUSION We observed that intramedullary administration of TXA in PFNA surgery for intertrochanteric fractures in elderly individuals resulted in less peri-operative blood loss and decreased transfusion rate, without any adverse effects, and is, thus, recommended.
Humans ; Tranexamic Acid/administration & dosage* ; Hip Fractures/surgery* ; Male ; Aged ; Female ; Fracture Fixation, Intramedullary/adverse effects* ; Blood Loss, Surgical/prevention & control* ; Antifibrinolytic Agents/administration & dosage* ; Aged, 80 and over ; Bone Nails ; Middle Aged ; Blood Transfusion/statistics & numerical data*

ObjectiveOur recent study has demonstrated that extracellular acidification promotes lipid accumulation in macrophages via the activation of acid sensing ion channel 1 (ASIC1), but the underlying mechanism remains unclear. This study aims to explore the effect of extracellular acidification on macrophage lipophagy and the underlying mechanism. MethodsRAW264.7 macrophages were incubated with 25 mg/Lox-LDL in a pH 6.5 culture medium for 24 h to build macrophage-derived foam cell models induced by extracellular acidification. Then, RAW264.7 macrophages were cultured in the acidic medium of pH 6.5 with or without PcTx-1 (ASIC1 specific blocker, 10 μg/L) or Nec-1 (RIP1 specific inhibitor, 20 μmol/L) for 24 h, intracellular lipid accumulation was observed by oil red O staining. The expressions of total ASIC1, plasma membrane ASIC1, RIP1, p-RIP1 Ser166, TFEB, p-TFEB Ser142, LC3 and p62 were measured by Western blot. The co-localization of lipids (indicated by Bodipy) with LC3II (autophagosomes) and LAMP1 (lysosomes) was analyzed by a confocal laser scanning microscopy, respectively. Morphological changes of lipophagy in the cells were observed by using transmission electron microscopy. ABCA1-mediated cholesterol efflux was determined by cholesterol fluorescence kits. ResultsCompared with pH 7.4+ox-LDL group, the intracellular lipid accumulation in the pH 6.5+ox-LDL group was significantly increased. Meanwhile, the expressions of plasma membrane ASIC1, p-RIP1 Ser166, p-TFEB Ser142, and p62 proteins were elevated significantly, while LC3II protein level and LC3II/LC3I ratio were decreased. Accordingly, compared with pH 7.4+ox-LDL group, the macrophage lipophagy of the pH 6.5+ox-LDL group was inhibited as indicated by the decreased localization of lipid droplets with LC3 and LAMP1, a decrease in the number of lipophagosomes as well as an increase in lipid droplets. Furthermore, ATP binding cassette transporter A1 (ABCA1)-dependent cholesterol efflux from the macrophages of pH 6.5+ox-LDL group reduced dramatically. However, these above effects of extracellular acidification on RAW264.7 macrophages were abolished by PcTx-1 and Nec-1, respectively. ConclusionThese findings suggest extracellular acidification promotes the phosphorylation of TFEB at Ser142 via activating ASIC1/RIP1 pathway, thereby impeding lipophagy in RAW 264.7 macrophages, and that ASIC1 may be a new potential target for preventing aberrant lipid accumulation diseases including atherosclerosis.

Magnetic beads (MB),composed of magnetic nanoparticles and biocompatible materials including cellulose,chitosan,silica and polystyrene,are ideal platforms for specific detection of cancer cells,virus and nucleic acids when loaded with antibodies,fluorescent and conjugation molecules. With the ease of separations using magnets,magnetic particles show tremendous advantages over other platforms and thus arising potentials in circulating tumor cell (CTC),virus (such as SARS-CoV-2) antibody and antigen detections,and nucleic acid extractions and purifications. In addition,when combined with microfluidic devices,magnetic particles can be used to develop detection platforms with high throughputs,as well as portable and point-of-care apparatus. In accompany with their huge potentials in all kinds of biomedical and clinical scenarios,magnetic particles based medical devices have been commercialized such as antigen test kits that have been commonly used during the pandemic. In this review,the progress in detailed antibody conjugation practice used in each application scenario based on MB platform was summarized and the commercialization of analytical devices combined with microfluidics and others was discussed.

A 31P-quantitative nuclear magnetic resonance(qNMR)method was established for simultaneous determination of sodium α-glycerophosphate,sodium β-glycerophosphate and phosphoric acid in concentrated divitamins and sodium phosphate syrup.The qNMR experimental conditions were optimized,including hexamethylphosphoramide as internal standard,20%deuterium oxide solution as solvent,zgig pulse sequence,delay time of 30 s,and scan number of 64.The 31P-NMR peaks atδ29.80 of hexamethylphosphoramide,δ0.69 of sodiumα-glycerophosphate,δ0.17 of sodiumβ-glycerophosphate andδ0.03 of phosphoric acid were chosen as the quantitative peaks(pH of the test solution was around 4.8).Method validation was performed in terms of precision(Relative standard deviation less than 0.6%),linearity(Correlative coefficient greater than 0.999),limit of detection(23.58 μg/mL for sodium glycerophosphate and 11.61 μg/mL for phosphoric acid)and limit of quantitation(78.60 μg/mL for sodium glycerophosphate and 38.70 μg/mL for phosphoric acid).The recoveries were 99.8%?103.2%,and relative standard deviations were 0.41%?1.98%.The results showed that the reliability of 31P-qNMR method were suitable for its intended use.Seven batches of concentrated divitamins and sodium phosphate syrups were tested by the established method,of which the total phosphorus content was consistent with that of colorimetry method,but the content of sodium glycerophosphate(Sum ofαtype andβtype)was relatively low,about 82%of the labeled amount.The content of phosphoric acid was high.This method simplified sample pretreatment and had high specificity,and was more suitable for determination and quality control of concentrated divitamins and sodium phosphate syrup.

AIM To observe the effects of Yiqi Fumai Lyophilized Injection on a mouse model of chronic heart failure after acute myocardial infarction and H9C2 cells with injury induced by oxygen and glucose deprivation.METHODS Thirty C57BL/6J mice were randomly divided into the sham-operation group,the model group,and the Yiqi Fumai group,among which the chronic heart failure model was made by ligation of anterior descending coronary artery and given 4 weeks corresponding drug administration.The H9C2 cells were divided into the normal group,the OGD model group,the low-dose,medium-dose and high-dose Yiqi Fumai groups,and the JQ1(BRD4 inhibitor)group.The following detections were conducted:heart ultrasound among the mice;the HE staining of the myocardial tissue for the observation of the morphological changes,spectrophotometry of cellular ATP level,JC-1 method for the determination of the mitochondrial membrane potential,RT-qPCR for the assessment of the mRNA expressions of ANP、BNP and BRD4,TUNEL method for the determination of level of cardiomyocytes apoptosis,and Western blot for the determination of the protein expressions of BRD4,AMPK and p-AMPK in both the mice and H9C2 cells.RESULTS Compared with the sham-operation group,the model group displayed decreased heart function(P＜0.01);obviously more hypertrophic or morphologically irregular cardiomyocytes;up-regulated mRNA expressions of ANP,BNP and BRD4(P＜0.01);increased cardiomyocyte apoptosis rate(P＜0.01);decreased p-AMPK/AMPK protein expression(P＜0.01);and increased BRD4 protein expression(P＜0.01).Compared with the model group,the Yiqi Fumai groups shared improvement in terms of all the aforementioned indices levels(P＜0.05,P＜0.01).Compared with the H9C2 cells of the normal group,those of the OGD model group displayed up-regulated mRNA expressions of ANP,BNP and BRD4(P＜0.01);increased apoptosis rate(P＜0.01);decreased p-AMPK/AMPK protein expression(P＜0.01);increased BRD4 protein expression(P＜0.01),and decreased mitochondrial membrane potential and ATP levels(P＜0.01).Compared with the OGD model group,the groups treated with either Yiqi Fumai or JQ1 demonstrated improvement in terms of the aforementioned indices levels(P＜0.05,P＜0.01).CONCLUSION Yiqi Fumai Lyophilized Injection exhibits its efficacy in improving cardiac function,myocardial energy metabolism,intracellular mitochondria dysfunction and biogenesis in a mouse model of chronic heart failure after myocardial infarction.The effects may be mediated by regulation of BRD4/AMPK signaling pathway.

Objective: To establish a nomogram prognostic model for predicting the 5-, 10-, and 15-year overall survival (OS) of non-metastatic renal cell carcinoma patients managed with radical nephrectomy (RN), compare the modelled results with the results of pure pathologic staging, the Karakiewicz nomogram and the Mayo Clinic Stage, Size, Grade, and Necrosis (SSIGN) score commonly used in foreign countries, and stratify the patients into different prognostic risk subgroups. Methods: A total of 1 246 non-metastatic renal cell carcinoma patients managed with RN in Sun Yat-sen University Cancer Center (SYSUCC) from 1999 to 2020 were retrospectively analyzed. Multivariate Cox regression analysis was used to screen the variables that influence the prognosis for nomogram establishment, and the bootstrap random sampling was used for internal validation. The time-receiver operating characteristic curve (ROC), the calibration curve and the clinical decision curve analysis (DCA) were applied to evaluate the nomogram. The prediction efficacy of the nomogram and that of the pure pathologic staging, the Karakiewicz nomogram and the SSIGN score was compared through the area under the curve (AUC). Finally, patients were stratified into different risk subgroups according to our nomogram scores. Results: A total of 1 246 patients managed with RN were enrolled in this study. Multivariate Cox regression analysis showed that age, smoking history, pathological nuclear grade, sarcomatoid differentiation, tumor necrosis and pathological T and N stages were independent prognostic factors for RN patients (all P<0.05). A nomogram model named SYSUCC based on these factors was built to predict the 5-, 10-, and 15-year survival rate of the participating patients. In the bootstrap random sampling with 1 000 iterations, all these factors occurred for more than 800 times as independent predictors. The Harrell's concordance index (C-index) of SYSUCC was higher compared with pure pathological staging [0.770 (95% CI: 0.716-0.823) vs 0.674 (95% CI: 0.621-0.728)]. The calibration curve showed that the survival rate as predicted by the SYSUCC model simulated the actual rate, while the clinical DCA showed that the SYSUCC nomogram has a benefit in certain probability ranges. In the ROC analysis that included 857 patients with detailed pathological nuclear stages, the nomogram had a larger AUC (5-/10-year AUC: 0.823/0.804) and better discriminating ability than pure pathological staging (5-/10-year AUC: 0.701/0.658), Karakiewicz nomogram (5-/10-year AUC: 0.772/0.734) and SSIGN score (5-/10-year AUC: 0.792/0.750) in predicting the 5-/10-year OS of RN patients (all P<0.05). In addition, the AUC of the SYSUCC nomogram for predicting the 15-year OS (0.820) was larger than that of the SSIGN score (0.709), and there was no statistical difference (P<0.05) between the SYSUCC nomogram, pure pathological staging (0.773) and the Karakiewicz nomogram (0.826). The calibration curve was close to the standard curve, which indicated that the model has good predictive performance. Finally, patients were stratified into low-, intermediate-, and high-risk subgroups (738, 379 and 129, respectively) according to the SYSUCC nomogram scores, among whom patients in intermediate- and high-risk subgroups had a worse OS than patients in the low-risk subgroup (intermediate-risk group vs. low-risk group: HR=4.33, 95% CI: 3.22-5.81, P<0.001; high-risk group vs low-risk group: HR=11.95, 95% CI: 8.29-17.24, P<0.001), and the high-risk subgroup had a worse OS than the intermediate-risk group (HR=2.63, 95% CI: 1.88-3.68, P<0.001). Conclusions: Age, smoking history, pathological nuclear grade, sarcomatoid differentiation, tumor necrosis and pathological stage were independent prognostic factors for non-metastasis renal cell carcinoma patients after RN. The SYSUCC nomogram based on these independent prognostic factors can better predict the 5-, 10-, and 15-year OS than pure pathological staging, the Karakiewicz nomogram and the SSIGN score of patients after RN. In addition, the SYSUCC nomogram has good discrimination, agreement, risk stratification and clinical application potential.
Humans ; Nomograms ; Retrospective Studies ; Carcinoma, Renal Cell/pathology* ; Prognosis ; Risk Factors ; Nephrectomy ; Kidney Neoplasms/pathology* ; Necrosis

Objective: To report the long-term survival of renal cell carcinoma (RCC) patients treated with radical nephrectomy in Sun Yat-sen University Cancer Center. Methods: We retrospectively analyzed the clinical, pathological and follow-up records of 1 367 non-metastatic RCC patients treated with radical nephrectomy from 1999 to 2020 in this center. The primary endpoint of this study was overall survival rate. Survival curves were estimated using the Kaplan-Meier method, and group differences were compared through Log-rank test. Univariate and multivariate Cox analysis were fit to determine the clinical and pathological features associated with overall survival rate. Results: A total of 1 367 patients treated with radical nephrectomy with complete follow-up data were included in the study. The median follow-up time was 52.6 months, and 1 100 patients survived and 267 died, with the median time to overall survival not yet reached. The 5-year and 10-year overall survival rates were 82.8% and 74.9%, respectively. The 5-year and 10-year overall survival rates of Leibovich low-risk patients were 93.3% and 88.2%, respectively; of Leibovich intermediate-risk patients were 82.2% and 72.3%, respectively; and of Leibovich high-risk patients were 50.5% and 30.2%, respectively. There were significant differences in the long-term survival among the three groups (P<0.001). The 10-year overall survival rates for patients with pT1, pT2, pT3 and pT4 RCC were 83.2%, 73.6%, 55.0% and 31.4%, respectively. There were significant differences among pT1, pT2, pT3 and pT4 patients(P<0.001). The 5-year and 10-year overall survival rates of patients with lymph node metastasis were 48.5% and 35.6%, respectively, and those of patients without lymph node metastasis were 85.1% and 77.5%, respectively. There was significant difference in the long-term survival between patients with lymph node metastasis and without lymph node metastasis. The 10-year overall survival rate was 96.2% for nuclear Grade 1, 81.6% for nuclear Grade 2, 60.5% for nuclear Grade 3, and 43.4% for nuclear Grade 4 patients. The difference was statistically significant. There was no significant difference in the long-term survival between patients with localized renal cancer (pT1-2N0M0) who underwent open surgery and minimally invasive surgery (10-year overall survival rate 80.5% vs 85.6%, P=0.160). Multivariate Cox analysis showed that age≥55 years (HR=2.11, 95% CI: 1.50-2.96, P<0.001), T stage(T3+ T4 vs T1a: HR=2.37, 95% CI: 1.26-4.46, P=0.008), local lymph node metastasis (HR=3.04, 95%CI: 1.81-5.09, P<0.001), nuclear grade (G3-G4 vs G1: HR=4.21, 95%CI: 1.51-11.75, P=0.006), tumor necrosis (HR=1.66, 95% CI: 1.17-2.37, P=0.005), sarcomatoid differentiation (HR=2.39, 95% CI: 1.31-4.35, P=0.005) and BMI≥24kg/m(2) (HR=0.56, 95%CI: 0.39-0.80, P=0.001) were independent factors affecting long-term survival after radical nephrectomy. Conclusions: The long-term survival of radical nephrectomy in patients with renal cell carcinoma is satisfactory. Advanced age, higher pathological stage and grade, tumor necrosis and sarcomatoid differentiation were the main adverse factors affecting the prognosis of patients. Higher body mass index was a protective factor for the prognosis of patients.
Humans ; Middle Aged ; Carcinoma, Renal Cell/secondary* ; Lymphatic Metastasis ; Retrospective Studies ; Neoplasm Staging ; Kidney Neoplasms/pathology* ; Prognosis ; Nephrectomy ; Survival Analysis ; Necrosis/surgery* ; Survival Rate

Objective: To establish a nomogram prognostic model for predicting the 5-, 10-, and 15-year overall survival (OS) of non-metastatic renal cell carcinoma patients managed with radical nephrectomy (RN), compare the modelled results with the results of pure pathologic staging, the Karakiewicz nomogram and the Mayo Clinic Stage, Size, Grade, and Necrosis (SSIGN) score commonly used in foreign countries, and stratify the patients into different prognostic risk subgroups. Methods: A total of 1 246 non-metastatic renal cell carcinoma patients managed with RN in Sun Yat-sen University Cancer Center (SYSUCC) from 1999 to 2020 were retrospectively analyzed. Multivariate Cox regression analysis was used to screen the variables that influence the prognosis for nomogram establishment, and the bootstrap random sampling was used for internal validation. The time-receiver operating characteristic curve (ROC), the calibration curve and the clinical decision curve analysis (DCA) were applied to evaluate the nomogram. The prediction efficacy of the nomogram and that of the pure pathologic staging, the Karakiewicz nomogram and the SSIGN score was compared through the area under the curve (AUC). Finally, patients were stratified into different risk subgroups according to our nomogram scores. Results: A total of 1 246 patients managed with RN were enrolled in this study. Multivariate Cox regression analysis showed that age, smoking history, pathological nuclear grade, sarcomatoid differentiation, tumor necrosis and pathological T and N stages were independent prognostic factors for RN patients (all P<0.05). A nomogram model named SYSUCC based on these factors was built to predict the 5-, 10-, and 15-year survival rate of the participating patients. In the bootstrap random sampling with 1 000 iterations, all these factors occurred for more than 800 times as independent predictors. The Harrell's concordance index (C-index) of SYSUCC was higher compared with pure pathological staging [0.770 (95% CI: 0.716-0.823) vs 0.674 (95% CI: 0.621-0.728)]. The calibration curve showed that the survival rate as predicted by the SYSUCC model simulated the actual rate, while the clinical DCA showed that the SYSUCC nomogram has a benefit in certain probability ranges. In the ROC analysis that included 857 patients with detailed pathological nuclear stages, the nomogram had a larger AUC (5-/10-year AUC: 0.823/0.804) and better discriminating ability than pure pathological staging (5-/10-year AUC: 0.701/0.658), Karakiewicz nomogram (5-/10-year AUC: 0.772/0.734) and SSIGN score (5-/10-year AUC: 0.792/0.750) in predicting the 5-/10-year OS of RN patients (all P<0.05). In addition, the AUC of the SYSUCC nomogram for predicting the 15-year OS (0.820) was larger than that of the SSIGN score (0.709), and there was no statistical difference (P<0.05) between the SYSUCC nomogram, pure pathological staging (0.773) and the Karakiewicz nomogram (0.826). The calibration curve was close to the standard curve, which indicated that the model has good predictive performance. Finally, patients were stratified into low-, intermediate-, and high-risk subgroups (738, 379 and 129, respectively) according to the SYSUCC nomogram scores, among whom patients in intermediate- and high-risk subgroups had a worse OS than patients in the low-risk subgroup (intermediate-risk group vs. low-risk group: HR=4.33, 95% CI: 3.22-5.81, P<0.001; high-risk group vs low-risk group: HR=11.95, 95% CI: 8.29-17.24, P<0.001), and the high-risk subgroup had a worse OS than the intermediate-risk group (HR=2.63, 95% CI: 1.88-3.68, P<0.001). Conclusions: Age, smoking history, pathological nuclear grade, sarcomatoid differentiation, tumor necrosis and pathological stage were independent prognostic factors for non-metastasis renal cell carcinoma patients after RN. The SYSUCC nomogram based on these independent prognostic factors can better predict the 5-, 10-, and 15-year OS than pure pathological staging, the Karakiewicz nomogram and the SSIGN score of patients after RN. In addition, the SYSUCC nomogram has good discrimination, agreement, risk stratification and clinical application potential.
Humans ; Nomograms ; Retrospective Studies ; Carcinoma, Renal Cell/pathology* ; Prognosis ; Risk Factors ; Nephrectomy ; Kidney Neoplasms/pathology* ; Necrosis

Objective: To report the long-term survival of renal cell carcinoma (RCC) patients treated with radical nephrectomy in Sun Yat-sen University Cancer Center. Methods: We retrospectively analyzed the clinical, pathological and follow-up records of 1 367 non-metastatic RCC patients treated with radical nephrectomy from 1999 to 2020 in this center. The primary endpoint of this study was overall survival rate. Survival curves were estimated using the Kaplan-Meier method, and group differences were compared through Log-rank test. Univariate and multivariate Cox analysis were fit to determine the clinical and pathological features associated with overall survival rate. Results: A total of 1 367 patients treated with radical nephrectomy with complete follow-up data were included in the study. The median follow-up time was 52.6 months, and 1 100 patients survived and 267 died, with the median time to overall survival not yet reached. The 5-year and 10-year overall survival rates were 82.8% and 74.9%, respectively. The 5-year and 10-year overall survival rates of Leibovich low-risk patients were 93.3% and 88.2%, respectively; of Leibovich intermediate-risk patients were 82.2% and 72.3%, respectively; and of Leibovich high-risk patients were 50.5% and 30.2%, respectively. There were significant differences in the long-term survival among the three groups (P<0.001). The 10-year overall survival rates for patients with pT1, pT2, pT3 and pT4 RCC were 83.2%, 73.6%, 55.0% and 31.4%, respectively. There were significant differences among pT1, pT2, pT3 and pT4 patients(P<0.001). The 5-year and 10-year overall survival rates of patients with lymph node metastasis were 48.5% and 35.6%, respectively, and those of patients without lymph node metastasis were 85.1% and 77.5%, respectively. There was significant difference in the long-term survival between patients with lymph node metastasis and without lymph node metastasis. The 10-year overall survival rate was 96.2% for nuclear Grade 1, 81.6% for nuclear Grade 2, 60.5% for nuclear Grade 3, and 43.4% for nuclear Grade 4 patients. The difference was statistically significant. There was no significant difference in the long-term survival between patients with localized renal cancer (pT1-2N0M0) who underwent open surgery and minimally invasive surgery (10-year overall survival rate 80.5% vs 85.6%, P=0.160). Multivariate Cox analysis showed that age≥55 years (HR=2.11, 95% CI: 1.50-2.96, P<0.001), T stage(T3+ T4 vs T1a: HR=2.37, 95% CI: 1.26-4.46, P=0.008), local lymph node metastasis (HR=3.04, 95%CI: 1.81-5.09, P<0.001), nuclear grade (G3-G4 vs G1: HR=4.21, 95%CI: 1.51-11.75, P=0.006), tumor necrosis (HR=1.66, 95% CI: 1.17-2.37, P=0.005), sarcomatoid differentiation (HR=2.39, 95% CI: 1.31-4.35, P=0.005) and BMI≥24kg/m(2) (HR=0.56, 95%CI: 0.39-0.80, P=0.001) were independent factors affecting long-term survival after radical nephrectomy. Conclusions: The long-term survival of radical nephrectomy in patients with renal cell carcinoma is satisfactory. Advanced age, higher pathological stage and grade, tumor necrosis and sarcomatoid differentiation were the main adverse factors affecting the prognosis of patients. Higher body mass index was a protective factor for the prognosis of patients.
Humans ; Middle Aged ; Carcinoma, Renal Cell/secondary* ; Lymphatic Metastasis ; Retrospective Studies ; Neoplasm Staging ; Kidney Neoplasms/pathology* ; Prognosis ; Nephrectomy ; Survival Analysis ; Necrosis/surgery* ; Survival Rate

Objective To investigate the titer stability of the harvest solution of severe acute respiratory syndrome coronavirus2(SARS-CoV-2)at 2 ～ 8 ℃ and the inactivation effect of β-propiolactone inactivator on the virus.Methods Three batches of SARS-CoV-2 harvest solution(batch numbers:202111001,202111002 and 202111003)were stored at 2 ～ 8 ℃ for 12 d and sampled every 3 d(0,3,6,9 and 12 d)for detection of the titers by Karber method;Three batches of virus harvest solution equilibrated overnight at 2 ～ 8 ℃ were inactivated by adding β-propiolactone at a volume fraction of 1∶4 000 and detected for the titers at different inactivation time points(0,0.5,1,1.5,2,3,4,8,16 and 24 h),of which samples inactivated for 8,16 and 24 h were taken for inactivation verification,and samples inactivated for 24 h were observed by transmission electron microscope.Results The titers of SARS-CoV-2 decreased with the prolongation of storage time at 2 ～8 ℃,which showed no obvious decrease during 0 ～ 3 d,while decreased from the initial 7.75,6 and 7.5 lgCCID_(50)/mL to5.75,4.625 and 6.25 lgCCID_(50)/mL on day 12,indicating that the virus activity showed a gradual decrease trend at 2 ～8 ℃；With the inactivation time,the virus titer decreased continuously and could not be detected after inactivation for 3 h.Transmission electron microscope observation showed that the inactivated virus particles were intact and the spike protein was evenly distributed.Conclusion The virulence of SARS-CoV-2 stored at 2 ～ 8 ℃ was unstable,so the subsequent inactivation and purification process should be carried out as soon as possible;The titer of virus could not be detected after3 h of inactivation,which provided a reference for the determination of the inactivation process.