ObjectiveThe purpose of this study was to investigate the effects of transcutaneous electrical acupoint stimulation (TEAS) on cognitive function of vascular dementia (VD) rats and its mechanism. MethodsVD rat model was established by modified two-vessel occlusion (2-VO). After modeling, TEAS and electroacupuncture (EA) were used to stimulate Baihui and Zusanli points of rats respectively for 14 d. After treatment, novel object recognition test, Morris water maze test, and Y maze test were used to evaluate the spatial memory and learning ability of rats. Hematoxylin and eosin staining was used to observe the morphology of hippocampal neurons. Transmission electron microscopy was used to observe the ultrastructure of hippocampal mitochondria. Enzyme-linked immunosorbent assay kits were used to detected the levels of SOD, CAT, GSH-Px, MDA and ROS in serum of rats. Western blot was used to detect the expression of PGC-1α, TFAM, HO-1, NQO1 proteins in the hippocampus, Keap1 protein in the cytoplasm and Nrf2, NRF1 proteins in the nucleus. ResultsAfter treatment for 14 d, compared to the model group, the escape latency of VD rats decreased, while the discrimination index, the times of rats crossing the original platform area, the residence time in the original platform quadrant, and the percentage of alternation increased. TEAS can improve the structure of hippocampal neurons and mitochondria of VD rats, showing that neurons were arranged more regularly and distributed more evenly, nuclear membrane and nucleoli were clearer, and mitochondrial swelling were reduced, mitochondrial matrix density were increased, and mitochondrial cristae were more obvious. The levels of SOD, GSH-Px and CAT in serum increased significantly, while the concentration of MDA and ROS decreased. TEAS also up-regulated the expression levels of PGC-1α TFAM, NQO1 and HO-1 proteins in the hippocampus and Nrf2, NRF1 proteins in the nucleus, but down-regulated the Keap1 protein in the cytoplasm. ConclusionTEAS can improve cognition, hippocampal neurons and mitochondrial structure of VD rats, and the effect is better than EA. The mechanism may be the activation of PGC-1α mediated mitochondrial biogenesis and antioxidant stress, which also provides a potential therapeutic technology and experimental basis for the treatment of VD.

This study aims to develop the pre-column derivatization high performance liquid chromatography(HPLC) method for the determination of 16 kinds of amino acids in Eucommia ulmoides leaves, and compare the content of amino acids in the leaves harvested at different time and under leaf-oriented cultivation mode(LCM) and arbor forest mode(AFM). The HPLC conditions are as below: phenyl isothiocyanate(PITC) as pre-column derivatization agent, Agilent ZORBAX C_(18 )column(4.6 mm×250 mm, 5 μm), mobile phase A of acetonitrile-water(80∶20), mobile phase B of 0.1 mol·L~(-1) sodium acetate solution-acetonitrile(94∶6), gradient elution, flow rate of 1.0 mL·min~(-1), injection volume of 5 μL, column temperature of 40 ℃, and detection wavelength of 254 nm. The HPLC profile indicated well separation of 16 kinds of amino acids and the amino acid content in E. ulmoides leaves was up to 16.26%. In addition, the amino acid content in leaves of E. ulmoides under LCM was higher than under AFM. The amino acid content varied with the harvesting time. Through orthogonal partial least squares discriminant analysis, the amino acids of E. ulmoides under LCM and AFM were compared, which can distinguish the leaves under LCM from those under AFM. Principal component analysis was applied to comprehensively score the amino acids of E. ulmoides leaves. The results showed that the score of leaves under LCM was higher than that under AFM. Nutritional evaluation results indicated that the proteins in E. ulmoides leaves belonged to high-quality vegetable proteins. The established method for the determination of amino acid content is reliable. With the amino acid content as index, the leaf quality of E. ulmoides under LCM is better than that under AFM. This study lays a theoretical basis for the promotion of LCM for E. ulmoides and the development of medicinal and edible products from E. ulmoides leaves.
Amino Acids/metabolism* ; Eucommiaceae/chemistry* ; Chromatography, High Pressure Liquid/methods* ; Plant Leaves/chemistry*

To study the effects of different drying methods on the quality of male flowers of Eucommia ulmoides(MFOEU), we treated fresh MFOEU samples with drying in the shade(DS), vacuum freeze drying(VFD), high-or low-temperature hot air drying(HTHAD, LTHAD), microwave drying(MD), and vacuum drying(VD), respectively. The color, total flavonoid content, total polysaccharide content, and main active components such as geniposide, geniposidic acid, rutin, chlorogenic acid, galuteolin, pinoresinol diglucoside, and aucubin in MFOEU were taken as the evaluation indicators. The quality of MFOEU was comprehensively evaluated by entropy weight method combined with color index method, partial least squares discriminant analysis and content clustering heat map. The experimental results showed that VFD and DS basically kept the original color of MFOEU. The MFOEU treated with MD had higher content of total polysaccharides, phenylpropanoids, lignans, and iridoids. The MFOEU treated with LTHAD had higher content of total flavonoids and that treated with VD had lower content of active components. According to the results of comprehensive evaluation, the quality of MFOEU dried with different methods followed the order of MD>HTHAD>VFD>LTHAD>DS>VD. Considering the color of MFOEU, the suitable drying methods were DS and VFD. Considering the color, active components, and economic benefits of MFOEU, MD was the suitable drying method. The results of this study are of a reference value for the determination of suitable methods for MFOEU processing in the producing areas.
Eucommiaceae/chemistry* ; Flowers/chemistry* ; Flavonoids/analysis* ; Rutin/analysis* ; Chlorogenic Acid/analysis*

Objective: To analyze the genetic characteristics of varicella-zoster virus (VZV) in people aged 20 years and under in Yichang City of Hubei Province from 2019 to 2020. Methods: Based on the Yichang Health Big Data Platform, we investigated cases 20 and under clinically diagnosed as herpes zoster in three hospitals from March 2019 to September 2020. Collecting vesicle fluid and throat swab samples of the cases and completing questionnaires to obtain basic information. Real-time fluorescent quantitative PCR was used for positive identification of the virus. PCR amplification of VZV's open reading frame (ORF) and sequencing of the products to determine the VZV genotype. Analyze mutations at some specific single nucleotide polymorphism (SNP) sites. Results: Among 46 cases of herpes zoster, the male to female ratio was 1.3∶1 (26∶20) and the age ranged from 7 to 20 years old. Fifteen cases had been vaccinated against varicella, including 13 and 2 cases of 1 and 2 doses, respectively. VZV strains were detected in 34 samples (73.91%), all belonging to Clade 2. Phylogenetic tree analysis of the nucleotide of ORF22 showed, compared with Clade 2 referenced strains, the sequence matching degree of nucleotide for all 34 samples was 99.0% to 100.0%. Conclusion: The main VZV strain causing herpes zoster in people aged 20 years and under in Yichang from 2019 to 2020 was Clade 2.
Humans ; Child ; Adolescent ; Young Adult ; Adult ; Herpesvirus 3, Human/genetics* ; Phylogeny ; Herpes Zoster/epidemiology* ; Polymorphism, Single Nucleotide ; Real-Time Polymerase Chain Reaction ; Nucleotides

Background: We found microRNA (miR)-1246 to be significantly differentially expressed between severe active alopecia areata (AA) patients and healthy individuals. Objective: To explore the role and mechanism of miR-1246 in severe AA. Methods: Expression of miR-1246, dual-specific tyrosine phosphorylation-regulated kinase 1A (DYRK1A), and nuclear factor of activated T cells 1c (NFATc1) in peripheral CD4+ T cells and in scalp tissues of patients were detected using RT-qPCR, Western blot, and immunohistochemistry assays. Peripheral CD4+ T cells from the AA patients were transfected with lentiviral vectors overexpressing miR-1246. RT-qPCR and Western blot analysis were used to measure mRNA or protein expression of retinoic-acid-receptor-related orphan nuclear receptor gamma (ROR-γt), interleukin (IL)-17, DYRK1A, NFATc1, and phosphorylated NFATc1. Flow cytometry was used to assay the CD4+ IL-17+ cells proportion. ELISA was used to measure cytokine levels. Results: miR-1246 levels decreased and DYRK1A and NFATc1 mRNA levels significantly increased in the peripheral CD4+ T cells and scalp tissues of severe active AA samples.NFATc1 protein expression was also significantly increased in the peripheral CD4+ T cells but not in the scalp tissues. NFATc1 positive cells were mainly distributed among infiltrating inflammatory cells around hair follicles. In peripheral CD4+ T cells of severe active AA, overexpression of miR-1246 resulted in significant downregulation of DYRK1A, NFATc1, ROR-γt, and IL-17 mRNA and phosphorylated NFATc1 protein, as well as a decrease in the CD4+ IL-17+ cells proportion and the IL-17F level. Conclusion miR-1246 can inhibit NFAT signaling and Th17 cell activation, which may be beneficial in the severe AA treatment.

This paper clarified the scientific connotation of the changes in cold and heat properties of Arisaematis Rhizoma and Arisaema Cum Bile through investigating the changes of substance and energy metabolism after drug intervention in the rats with normal and cold/heat syndrome, so as to improve the method of evaluating the drug properties of Chinese medicine. After one week of adaptive feeding, healthy male SD rats were randomly divided into three parts: normal rats, heat syndrome rat models, and cold syndrome rat models. Through ice water bath and oral euthyrox(120 μg·kg~(-1)), the models of cold syndrome and heat syndrome were induced, respectively. The models were made at 9:00 am. and administrated by gavage at 3:00 pm. every day. All administration groups were administrated with Arisaematis Rhizoma and Arisaema Cum Bile decoction, respectively, and the blank group was given the same dose of normal saline. After continuous administration for 15 d, the rats were anesthetized by chloral hydrate, blood was taken from abdominal aorta, and the hearts and livers were removed and stored at-80 ℃. The changes in the body weight and anal temperature of rats during administration were detected, and the liver coefficient of rats was detected after removing the liver. Enzyme-linked immunosorbent assay(ELISA) was adopted to detect the expression level of the indexes related to substance and energy metabolism in liver and heart of rat, and Western blot was used to detect the expression of key proteins in AMPK/mTOR signaling pathway for further verification. The results showed that Arisaematis Rhizoma enhanced the expression level of enzymes related to substance and energy metabolism in the normal and cold and heat syndrome rat models, and increased anal temperature, which exhibited warm(hot) drug property. Arisaema Cum Bile inhibited the level of substance and energy metabolism in rats, and reduced anal temperature, which showed cold(cool) drug property. Chinese Pharmacopoeia has recorded "Arisaematis Rhizoma has warm property and Arisaema Cum Bile has cool property", which is consistent with the phenomenon in this study. Therefore, it is feasible to evaluate the drug properties of Chinese medicine based on the substance and energy metabolism of normal and cold/heat syndrome model rats, which completes the method of evaluating drug properties of Chinese medicine.
AMP-Activated Protein Kinases ; Animals ; Arisaema/chemistry* ; Bile ; Chloral Hydrate ; Cold-Shock Response/drug effects* ; Drugs, Chinese Herbal/therapeutic use* ; Energy Metabolism ; Heat Stroke/therapy* ; Hot Temperature ; Male ; Rats ; Rats, Sprague-Dawley ; Saline Solution ; Syndrome ; TOR Serine-Threonine Kinases ; Thyroxine ; Water

Objective: To reassess the predictors for response at 6 months in patients with severe or very severe aplastic anemia (SAA/VSAA) who failed to respond to immunosuppressive therapy (IST) at 3 months. Methods: We retrospectively analyzed the clinical data of 173 patients with SAA/VSAA from 2017 to 2018 who received IST and were classified as nonresponders at 3 months. Univariate and multivariate logistic regression analysis were used to evaluate factors that could predict the response at 6 months. Results: Univariate analysis showed that the 3-month hemoglobin (HGB) level (P=0.017) , platelet (PLT) level (P=0.005) , absolute reticulocyte count (ARC) (P<0.001) , trough cyclosporine concentration (CsA-C0) (P=0.042) , soluble transferrin receptor (sTfR) level (P=0.003) , improved value of reticulocyte count (ARC(△)) (P<0.001) , and improved value of soluble transferrin receptor (sTfR(△)) level (P<0.001) were related to the 6-month response. The results of the multivariate analysis showed that the PLT level (P=0.020) and ARC(△) (P<0.001) were independent prognostic factors for response at 6 months. If the ARC(△) was less than 6.9×10(9)/L, the 6-month hematological response rate was low, regardless of the patient's PLT count. Survival analysis showed that both the 3-year overall survival (OS) [ (80.1±3.9) % vs (97.6±2.6) %, P=0.002] and 3-year event-free survival (EFS) [ (31.4±4.5) % vs (86.5±5.3) %, P<0.001] of the nonresponders at 6 months were significantly lower than those of the response group. Conclusion: Residual hematopoietic indicators at 3 months after IST are prognostic parameters. The improved value of the reticulocyte count could reflect whether the bone marrow hematopoiesis is recovering and the degree of recovery. A second treatment could be performed sooner for patients with a very low ARC(△).
Anemia, Aplastic/drug therapy* ; Antilymphocyte Serum/therapeutic use* ; Cyclosporine/therapeutic use* ; Humans ; Immunosuppression Therapy ; Immunosuppressive Agents/therapeutic use* ; Prognosis ; Receptors, Transferrin/therapeutic use* ; Retrospective Studies ; Treatment Outcome

Objective:To investigate the influences of age-adjusted Charlson comorbidity index (ACCI) on prognosis of patients undergoing laparoscopic radical gastrectomy.Methods:The retrospective cohort study was conducted. The clinicopathological data of 242 gastric cancer patients who underwent laparoscopic radical gastrectomy in 19 hospitals of the Chinese Laparoscopic Gastrointestinal Surgery Study Group-04 study, including 54 patients in Fujian Medical University Union Hospital, 32 patients in the First Hospital of Putian City, 32 patients in Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine, 31 patients in Zhangzhou Affiliated Hospital of Fujian Medical University, 17 patients in Nanfang Hospital of Southern Medical University, 11 patients in the First Affiliated Hospital with Nanjing Medical University, 8 patients in Qinghai University Affiliated Hospital, 8 patients in Meizhou People′s Hospital, 7 patients in Fujian Provincial Hospital, 6 patients in Zhongshan Hospital of Fudan University, 6 patients in Longyan First Hospital, 5 patients in the First Affiliated Hospital of Xinjiang Medical University, 5 patients in the First Hospital Affiliated to Army Medical University, 4 patients in the Second Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, 4 patients in West China Hospital of Sichuan University, 4 patients in Beijing University Cancer Hospital, 3 patients in the First Affiliated Hospital of Xiamen University, 3 patients in Guangdong Provincial People′s Hospital, 2 patients in the First Affiliated Hospital of Xi′an Jiaotong University, from September 2016 to October 2017 were collected. There were 193 males and 49 females, aged 62(range, 23?74)years. Observation indicators: (1) age distribution, comorbidities and ACCI status of patients; (2) the grouping of ACCI and comparison of clinicopathological characteristics of patients in each group; (3) incidence of postoperative early complications and analysis of factors affecting postoperative early complications; (4) follow-up; (5) analysis of factors affecting the 3-year recurrence-free survival rate of patients. Follow-up was conducted using outpatient examination or telephone interview to detect postoperative survival of patients up to December 2020. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the t test. Measurement data with skewed distribution were represented as M( Q1, Q3) or M(range), and comparison between groups was conducted using the Mann-Whitney U test. Count data were described as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Comparison of ordinal data was conducted using the nonparametric rank sum test. The X-Tile software (version 3.6.1) was used to analyze the best ACCI grouping threshold. The Kaplan-Meier method was used to calculate survival rates and draw survival curves. The Log-Rank test was used for survival analysis. The Logistic regression model was used to analyze the factors affecting postoperative early complications. The COX proportional hazard model was used for univariate and multivariate analyses of factors affecting the 3-year recurrence-free survival rate of patients. Multivariate analysis used stepwise regression to include variables with P<0.05 in univariate analysis and variables clinically closely related to prognosis. Results:(1) Age distribution, comor-bidities and ACCI status of patients. Of the 242 patients, there were 28 cases with age <50 years, 68 cases with age of 50 to 59 years, 113 cases with age of 60 to 69 years, 33 cases with age of 70 to 79 years. There was 1 patient combined with mild liver disease, 1 patient combined with diabetes of end-organ damage, 2 patients combined with peripheral vascular diseases, 2 patients combined with peptic ulcer, 6 patients combined with congestive heart failure, 8 patients combined with chronic pulmonary diseases, 9 patients with diabetes without end-organ damage. The ACCI of 242 patients was 2 (range, 0-4). (2) The grouping of ACCI and comparison of clinicopathological characteristics of patients in each group. Results of X-Tile software analysis showed that ACCI=3 was the best grouping threshold. Of the 242 patients, 194 cases with ACCI <3 were set as the low ACCI group and 48 cases with ACCI ≥3 were set as the high ACCI group, respectively. Age, body mass index, cases with preoperative comorbidities, cases of American Society of Anesthesiologists classification as stage Ⅰ, stage Ⅱ, stage Ⅲ, tumor diameter, cases with tumor histological type as signet ring cell or poorly differentiated adenocarcinoma and cases with tumor type as moderately or well differentiated adenocarcinoma, cases with tumor pathological T staging as stage T1, stage T2, stage T3, stage T4, chemotherapy cycles were (58±9)years, (22.6±2.9)kg/m 2, 31, 106, 85, 3, (4.0±1.9)cm, 104, 90, 16, 29, 72, 77, 6(4,6) in the low ACCI group, versus (70±4) years, (21.7±2.7)kg/m 2, 23, 14, 33, 1, (5.4±3.1)cm, 36, 12, 3, 4, 13, 28, 4(2,5) in the high ACCI group, showing significant differences in the above indicators between the two groups ( t=-14.37, 1.98, χ2=22.64, Z=-3.11, t=-2.91, χ2=7.22, Z=-2.21, -3.61, P<0.05). (3) Incidence of postoperative early complications and analysis of factors affecting postoperative early complications. Of the 242 patients, 33 cases had postoperative early complications, including 20 cases with local complications and 16 cases with systemic complica-tions. Some patients had multiple complications at the same time. Of the 20 patients with local complications, 12 cases had abdominal infection, 7 cases had anastomotic leakage, 2 cases had incision infection, 2 cases had abdominal hemorrhage, 2 cases had anastomotic hemorrhage and 1 case had lymphatic leakage. Of the 16 patients with systemic complications, 11 cases had pulmonary infection, 2 cases had arrhythmias, 2 cases had sepsis, 1 case had liver failure, 1 case had renal failure, 1 case had pulmonary embolism, 1 case had deep vein thrombosis, 1 case had urinary infection and 1 case had urine retention. Of the 33 cases with postoperative early complications, there were 3 cases with grade Ⅰ complications, 22 cases with grade Ⅱ complications, 5 cases with grade Ⅲa complications, 2 cases with grade Ⅲb complications and 1 case with grade Ⅳ complica-tions of Clavien-Dindo classification. Cases with postoperative early complications, cases with local complications, cases with systemic complications were 22, 13, 9 in the low ACCI group, versus 11, 7, 7 in the high ACCI group, respectively. There were significant differences in cases with postoperative early complications and cases with systemic complications between the two groups ( χ2=4.38, 4.66, P<0.05), and there was no significant difference in cases with local complications between the two groups ( χ2=2.20, P>0.05). Results of Logistic regression analysis showed that ACCI was a related factor for postoperative early complications of gastric cancer patients undergoing laparoscopic radical gastrectomy [ odds ratio=2.32, 95% confidence interval ( CI) as 1.04-5.21, P<0.05]. (4) Follow-up. All the 242 patients were followed up for 36(range,1?46)months. During the follow-up, 53 patients died and 13 patients survived with tumor. The 3-year recurrence-free survival rate of the 242 patients was 73.5%. The follow-up time, cases died and cases survived with tumor during follow-up, the 3-year recurrence-free survival rate were 36(range, 2-46)months, 29, 10, 80.0% for the low ACCI group, versus 35(range, 1-42)months, 24, 3, 47.4% for the high ACCI group. There was a significant difference in the 3-year recurrence-free survival rate between the two groups ( χ2=30.49, P<0.05). (5) Analysis of factors affecting the 3-year recurrence-free survival rate of patients. Results of univariate analysis showed that preoperative comorbidities, ACCI, tumor diameter, histological type, vascular invasion, lymphatic invasion, neural invasion, tumor pathological TNM staging, postoperative early complications were related factors for postoperative 3-year recurrence-free survival rate of gastric cancer patients undergoing laparoscopic radical gastrectomy [ hazard ratio ( HR)=2.52, 3.64, 2.62, 0.47, 2.87, 1.90, 1.86, 21.77, 1.97, 95% CI as 1.52-4.17, 2.22-5.95, 1.54-4.46, 0.27-0.80, 1.76-4.70, 1.15-3.12, 1.10-3.14, 3.01-157.52, 1.11-3.50, P<0.05]. Results of multivariate analysis showed that ACCI, tumor pathological TNM staging, adjuvant chemotherapy were indepen-dent influencing factors for postoperative 3-year recurrence-free survival rate of gastric cancer patients undergoing laparoscopic radical gastrectomy ( HR=3.65, 11.00, 40.66, 0.39, 95% CI as 2.21-6.02, 1.40-86.73, 5.41-305.69, 0.22-0.68, P<0.05). Conclusions:ACCI is a related factor for post-operative early complications of gastric cancer patients undergoing laparos-copic radical gastrectomy. ACCI, tumor pathological TNM staging, adjuvant chemotherapy are indepen-dent influencing factors for postoperative 3-year recurrence-free survival rate of gastric cancer patients undergoing laparoscopic radical gastrectomy.

Objective: To analyse the clinical application of thoracodorsal artery perforator flaps (TDAPF) in the repair of head and neck defects. Methods: A retrospective review was conducted on 38 patients with oral and maxillofacial head and neck malignant tumors who underwent radical resection of oral and oropharyngeal carcinoma and TDAPF repair in the Department of Oral and Maxillofacial Head and Neck Oncology of the Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from June 2017 to November 2018. Among them, 32 were males and 6 were females, aged 30-74 years. Flap size, vessel pedicle length, diameter and number of perforators, and flap fat thickness were recorded and counted. Elasti Meter and Skin Fibro Meter were applied to measure the skin elasticity and hardness in the donor areas of 4 kinds of skin flaps before the flap preparation. SPSS 19.0 statistical software was used for statistical analysis of the data. Results: All the flaps survived (100%). The mean elasticity of TDAPF [(41.2±12.9) N/m] was significantly lower than that of anterolateral thigh [(77.6±23.3) N/m, χ²=88.89, P<0.05], anterolateral thigh [(62.6±17.7) N/m, χ²=59.99, P<0.05] and or forearm flap [(51.7±8.6) N/m, χ²=37.82, P<0.05]. The hardness of TDAPF [(0.037±0.016) N] was also significantly lower than that of anterolateral femoral [(0.088±0.019) N, F=93.27, P<0.05], anteromedial femoral [(0.059±0.020) N, F=25.71, P<0.05] or forearm flap [(0.062±0.016) N, F=29.11, P<0.05]. Follow-up period ranged from 2 to 14 months. The 38 patients treated with TDAPF had a good recovery of the functions in the recipient areas, and the scars of the donor areas were not obvious after surgery, without serious complications. Conclusion: TDAPF is suitable for reconstruction of head and neck defect, with ductile texture and good recovery of the morphology and function of head and neck.
China ; Female ; Femoral Artery/surgery* ; Humans ; Male ; Perforator Flap ; Reconstructive Surgical Procedures ; Retrospective Studies ; Skin Transplantation ; Thigh/surgery*

Objective:To analyze the epidemiological characteristics of a family and workplace clustering of COVID-19， identify the source of infection and the transmission chain， and provide evidence for prevention and control of COVID-19 pandemic. Method:Field epidemiological method was used to conduct the investigation of confirmed cases and close contacts in this cluster. Data were analyzed with descriptive method. Real-time fluorescent quantitative PCR （RT-PCR） was used to detect the novel coronavirus nucleic acid in the collected respiratory tract samples. Results:A total of 18 epidemiological related cases were collected including 16 confirmed cases and 2 cases of asymptomatic infections. The involved places included 1 beauty clinic workplace and 3 families. Seven cases were males and 11 cases were females， with the minimum， maximum and median age of 3， 65 and 32 years old， respectively. Among them， the employees attack rate was 9.80% （10/102）， the family attack rate was 7.70% （5/78）， and the customer attack rate was 0.58% （1/173）. Positive nucleic acid test result in the respiratory tract sample of asymptomatic infection lasted for more than 2 months. Conclusions:The cause of this clustered COVID-19 epidemic is that the workplace environment is relatively closed with clustering crowds， and the source of imported infection is not discovered in time， which lead to a point-source outbreak and spread through family close contacts and clustering.