Objective:To investigate the whole genome characteristics and mutation of imported 2019-nCoV and trace potential source at the genomics level, the viral genomes from the specimens of a cluster of COVID-19 cases which were imported from a freighter were directly sequenced and determined by high-throughput sequencing technology and bioinformatics analysis.Methods:Throat swab specimens from the 8 confirmed cases of COVID-19 from the same freighter were collected to perform the whole genome sequencing for 2019-nCoV using the targeted genome amplification, combined with Ion S5 next-generation sequencing (NGS) technology. Varieties of online virus analysis platforms was used to classify the viruses and analyze mutation sites in the whole genome. Phylogenetic analysis software was used to construct a phylogenetic tree for the viruses, combined with the epidemiological data of the case, to speculate about the source of the viruses.Results:Eight complete genome sequences of 2019-nCoV was successfully obtained. The complete genomes of the viruses were 29, 822-29, 865 bp in length, with the average sequencing depth of 11 928×-33 588× and the coverage of 99.73%-99.87%; the result of Pangolin classification showed that all the eight 2019-nCoV genomes belong to VOC/Delta (B.1.617.2) lineage. The result of whole genome mutation analysis showed that compared with the Wuhan reference strain, the median number of nucleotide mutations in the eight 2019-nCoV genome sequences was 35 (31 to 38), and the median number of amino acid mutations was 26 (24-28); the mutation sites were distributed in 8 gene coding regions (ORF1a, ORF1b, S, ORF3a, M, ORF7a, ORF8, N). Further analysis revealed that eight 2019-nCoV genomes contained 23 characteristic mutation sites belonging to the Delta (B.1.617.2·AY.2) variants of 2019-nCoV. Since the mutation sites among the eight 2019-nCoV genomes were not completely overlapped, and the epidemiological survey report showed that the freighter stopped at multiple ports and had personnel alternation, it was speculated that the clustered COVID-19 cases might have different origins. Phylogenetic analysis showed that all the eight 2019-nCoV genomes were on the AY.2 sub-lineage of the B. 1.617.2 lineage. This result was consistent with the result of Pangolin classification and mutation analysis.Conclusions:In this study, 8 whole genome sequences of Delta variants were obtained through NGS technology from the clustered COVID-19 cases which were imported from a freighter. The sequencing method and analysis result in this study could provide reference for the 2019-nCoV mutation analysis and tracing the source of the COVID-19 cases for the prevention and control of the COVID-19 epidemic.

Objective:To analyze the transmissible characteristics of imported COVID-19 cases in Xiamen.Methods:The nasopharyngeal swabs and serum specimens were collected from inbound passengers on the same flight. The nucleic acid and antibodies to SARS-CoV-2 were detected respectively. The type of COVID-19 was determined according to the condition. The mode of transmission was analyzed according to the incidence and laboratory diagnosis of positive cases, and seats of cases on the plane.Results:Five cases of common type, 3 cases of mild type and 1 case of asymptomatic infection were found in the same Russian flight. Three cases, 5 cases, 1 case and 1 case were detected for nucleic acid on November 21, 22, 25 and 26, 2020. The whole genome sequence was obtained in 3 cases and 85% in 1 case. According to epidemiology, evolutionary characteristics of virus genome, Results of qPCR and antibody and case seating, the risk of transmission in aircraft cabin was analyzed.Conclusions:This is COVID-19 cases reports of inbound personnel in aircraft, and there is a risk of transmission in the cabin. The imported cases were isolated timely and effectively with the whole closed-loop. No other cases of infection occurred. This report provides a reference for the detection and prevention of transmission of cases imported by aircraft.

Objective:To analysis effectiveness of the "14 plus 7 day quarantine" and "nucleic acid plus total antibody testing" strategy (combined screening strategy) for screenin the imported patients with COVID-19 in Xiamen.Methods:The study populations were overseas travelers arriving in Xiamen from March 17 to December 31, 2020, and overseas travelers who had quarantine outside Xiamen for less than 21 days from July 18 to December 31, 2020. Data were collected and analyzed on the timing of detection, pathways, and test results of the imported patients with COVID-19 after implementing combined screening strategy.Results:A total of 304 imported patients with COVID-19 were found from 174 628 overseas travelers and 943 overseas travelers from other cities. A total of 163 cases (53.6%) were diagnosed by multitime, multisite intensive nucleic acid testing after positive finding in total antibody testing. Among them, 27 (8.9%) were first positive for nucleic acid in 14 plus 7 day quarantine and 136 were first positive for nucleic acid in 14-day quarantine. Only 8 of these individuals were tested positive for nucleic acid after positive total antibody testing. The other 128 individuals were tested positive for nucleic acid after being negative for average 2.3 times (maximum of 6 times). Aditional 155 cases might be detected by using the combined "14 plus 7 day quarantine" and " nucleic acid plus total antibody testing" strategy compared with "14-day quarantine and nucleic acid testing" strategy, accounting for 51.0% of the total inbound infections. So the combined screening strategy doubled the detection rate for imported patients with COVID-19. No second-generation case caused by overseas travelers had been reported in Xiamen as of February 26, 2021.Conclusions:Xiamen's combined screening strategy can effectively screen the imported patients with COVID-19 who were first positive for nucleic acid after 14 day quarantine. Compared with "14 day quarantine and nucleic acid testing", the combined screening strategy improved detection rate and further reduced the risk of the secondary transmission caused by the imported patients with COVID-19.

OBJECTIVE To investigate the protective effect of sGC003,a novel agonist of soluble guanylate cyclase,on endothelin-1(ET-1)-induced cardiomyocyte hypertrophy. METHODS Cardiomy?ocytes were isolated from neonatal Sprague-Dawley rats using serial enzymatic digestion and then incubated with ET-1 10 nmol·L-1 in the absence or presence of sGC003 0.01,0.1 and 1.0μmol·L-1. Hyper?trophic responses including the cardiomyocyte area(Image-Pro Plus 6.0),the expression of atrial natri?uretic peptide gene(ANP)mRNA(RT-PCR method)and total protein content(BCA method)were detect?ed. RESULTS After 48 h stimulation with ET-1 10 nmol·L-1,the cardiomyocyte area increased by 80%(P<0.01),the total protein content increased by 120%(P<0.01) and the expression of ANP mRNA up-regulated by 140%(P<0.01). sGC003 0.01,0.1 and 1.0μmol · L-1 elicited antihypertrophic actions, including inhibition of ET-1-mediated increase in the cardiomyocyte area(P<0.01),raised total protein content(P<0.05)and upregulation of ANP mRNA(P<0.05). CONCLUSION sGC003 has protective,car?diomyocyte-selective antihypertrophic effects in vitro.

Objective To systematically evaluate the association between lactotransferrin(LTF) gene rs1126478 polymor‐phism and caries susceptibility .Methods The published literatures on the association between LTF gene rs1126478 polymorphism and caries susceptibility were retrived from the electronic databases of Pubmed ,Web of science ,Embase ,EBSCO ,Springerlink , CNKI ,VIP ,Wanfang and CBM by computer .The pooled odds ratios (ORs) and its 95% confidence intervals (95% CIs) were used as the effect indicators .The statistical analysis was performed by using the RevMan 5 .2 and Stata 12 .0 softwares .The bias evalua‐tion and sensitivity analysis were also performed .Results A total of 5 case‐control studies involving 720 cases and 412 controls were included .The meta analysis results showed that no statistical significance in the association between LTF gene rs1126478 pol‐ymorphism and caries susceptibility was revealed in all four genetic models (GG+ AG vs .AA :P= 0 .75 ,OR= 0 .93 ,95% CI=0 .59-1 .46 ;G vs .A :P=0 .88 ,OR=0 .97 ,95% CI=0 .68 -1 .38 ;GG vs .AA :P=0 .84 ,OR=1 .07 ,95% CI =0 .57 -1 .99 ;GG vs .AG+AA :P=0 .52 ,OR=1 .12 ,95% CI = 0 .79-1 .58) .Similarly ,the subgroup analysis by ethnicity showed no statistical sig‐nificance in the onset risk between Caucasian and Asian populations as well (both P>0 .05) .Conclusion The LTF gene rs1126478 polymorphism may have no relation with the susceptibility to caries .

OBJECTIVE To analyze impulsive-like behaviors of SD rats induced by pramipexole in Y-maze avoidance tasks. METHODS Behaviors of SD rats in Y-maze avoidance tasks were recorded with a camera and analyzed by Noldus Etho Vision XT8 software after acute subcutaneous injection of pramipexole(0.1,1 and 10 mg · kg-1),including right reaction numbers of 20 consecutive avoidance tasks,shuttle number of times between the three arms of Y-maze, distance covered in Y-maze and time spent in safe arms during 20 consecutive avoidance tasks. Then,the prepulse inhibition(PPI)of the startle reflex test was used to assess the effect of pramipexole on sensorimotor gating (SG). Effects of pramipexole on the dialyzed content of monoamine neurotransmitter and its metabolites in the striatum and amygdala of SD rats were measured by microdialysis in vivo. RESULTS Compared with normal control group,the rats of pramipexole group showed a significant increase in the shuttle number of times and distance covered in Y-maze between Y-maze avoidance tasks(P<0.01),but a statistically significant decrease in the time spent in safe arms(P<0.01),while the number of right reactions in Y-maze avoidance tasks was not changed. Such premature responses were quite similar to certain impulsive-compulsive behaviors in rodent models,such as five-choice serial reaction time tasks. In the PPI test,pramipexole displayed an impairing effect on SG(P<0.01). The microdialysis results showed that there was an increase of dopamine and 5-hydroxytryptamine in the striatum of pramipexole group, but not statistically significant. Monoamine neurotransmitters and their metabolites were not significantly changed in the amygdala. CONCLUSION Pramipexole can induce impulsive-compulsive behaviors in Y-maze avoidance tasks,which might be attributed to impaired SG.

Objective To establish the quality standard of Radix Toddaliae Asiaticae. Methods Thin layer chromatography ( TLC) and high performance liquid chromatography ( HPLC) were used to identify and determine chloride nitidine and toddalolactone in Radix Toddaliae Asiaticae. The moisture and total ash contents were detected according to the methods recorded in appendix of Chinese Pharmacopeia (2010 edition) . Results Toddalolactone and chloride nitidine were detectable by TLC, the spots were clear and the dissociation was good. The established HPLC method was simple and accurate. The linear ranges of toddalolactone and chloride nitidine in Radix Toddaliae Asiaticae were 2.84~42.6 μg/mL and 25.6~385 μg/mL, and their recovery rates were 99.2 % ( RSD=1.12%) and 100 % ( RSD=0.71%) , respectively. The content of moisture was in the range of 75.8~98.9 mg/g and that of total ash was in the range of 12.4~33.6 mg/g. Conclusion The developed method is specific and accurate, and can provide useful reference for establishing quality standard of Radix Toddaliae Asiaticae.

BACKGROUND:Xenogeneic bone has a natural porous structure that is similar to human bone. In the treatment of bone defects, the porous structure is helpful to guide bone regeneration, but different degrees of immune responses wil be caused during the implantation process. OBJECTIVE:To prepare a freeze-dried antigen-extracted sheep cancelous bone scaffold and to evaluate its biocompatibility. METHODS: The sheep vertebral cancelous bone was colected to prepare two kinds of antigen-extracted heterologous bone scaffolds that were treated with chemical methods as chemical group and treated with chemical methods+cryopreservation at a-80℃ refrigerator for 4 weeks+drying in vacuum apparatus+60 RESULTS AND CONCLUSION:Freeze-dried bone had no cytotoxicity, no acute toxicity and heat reaction, and was negative for the intracutaneous stimulation test. The scaffold in the chemical group had cytotoxicity and mild irradiation as freeze-dried bone group. (1)Cytotoxicity test: Bone marrow mesenchymal stem cels isolated from sheep were cultured in extracts of the chemical group, free-dried bone group and Dulbecco’s modified Eagle’s medium/Ham’s nutrient mixture F-12. (2) Heat reaction and acute toxicity tests: Extracts from the chemical group, freeze-dried bone group and normal saline were respectively injected into the ear vein of rabbits. (3) Intracutaneous stimulation test: Extracts from the chemical group, freeze-dried bone group and normal saline were respectively injected subcutaneously into the back of rabbits. Co acute toxicity reaction, sent heat source and had mild irritation. Results show that after freeze drying processing, the sheep vertebral cancelous bone has good biocompatibility, can meet the requirements of bone tissue engineering, but the bone that through chemical processing exhibits a relatively poor biocompatibility that cannot achieve the safety standard of biological scaffold materials.

BACKGROUND:Xenogeneic bone structure and biological characteristics are similar to human bone tissue, and the xenogeneic bone has a decreased antigenicity after physicochemical treatment, with a natural porous structure and rich source, and can be kept for a long time, which is considered to be an effective way to solve the shortage of the autogenous bone and al ograft bone.
OBJECTIVE:To compare the physical and chemical properties of xenogenic bone materials prepared by two different methods.
METHODS:Sheep cancellous bone treated with chemical method was placed into the muffle furnace at 1 000 ℃for 2 hours to prepare calcined bone. Another cancellous bone was placed into an 80 ℃ refrigerator for 4 weeks and then placed into a vacuum instrument to prepare freeze-dried bone. Cancellous bone rinsed with ultra-pure water served as controls.
RESULTS AND CONCLUSION: Three groups of samples retained three-dimensional porous structure which similar with human bone tissue under microscopic observation. The framework was stil intact, with a smal pore of 55-650μm and high porosity of 65%-80%. For the calcined bone, the toughness was decreased and the brittleness increased significantly, but the freeze-dried bone had a little changes in the mechanical properties. Through diffraction analysis, hydroxyapatite was the main composition of the three groups. However, there was a smal amount ofβ-tricalcium phosphate in the calcined bone. Spectrum analysis confirmed that calcium and phosphorus content in these three groups were al close to the human body. The results suggest the cancellous bone treated with these two methods is similar to human bone structure, and the major elements are close to the body. In addition, the cancellous bone after processing has enough smal pore and higher porosity. However, calcination process has a more influence on the mechanical property of scaffold materials, and the freeze-dried bone has a little change but the antigen cannot be completely removed that can reach the basic requirements.

0.05),but these positive rates were notable decreased comparing with nPCR and immunohistochemistry techniques(P