Objective:To investigate the phylogenetic and antigenic characteristics of hemagglutinin (HA) gene of influenza B/Victoria lineage (BV) viruses in Beijing during the 2021-2022 influenza surveillance season, and to analyze whether the circulating BV viruses match the vaccine strain.Methods:Pharyngeal swab specimens from influenza like-illness (ILI) cases in the 2021-2022 influenza surveillance season were collected from surveillance network labs in Beijing and cultured in MDCK cells and chicken embryo to isolate BV viruses. Nucleic acids of the viruses were extracted, and the HA gene was amplified and sequenced. The nucleotide and amino acid sequence identity of the HA gene was analyzed using MEGA5.0 software. A phylogenetic tree of HA gene was constructed using the maximum likelihood method. The N-glycosylation sites in HA were predicted online. Three-dimensional structure of HA was constructed using SWISS-MODEL homologous modeling. Hemagglutination inhibition (HI) test was performed to analyze the antigenicity of BV viruses.Results:A total of 402 BV viruses were collected and 58 strains with full-length HA gene sequences were chosen for further analysis. Compared with the HA gene of this year′s vaccine strain (B/Washington/02/2019), there were 27 amino acid mutations, 11 of which were located in four different antigenic determinants. The phylogenetic analysis revealed that three subgroups of 1A.3, 1A.3a1, and 1A.3a2 co-circulated in Beijing with 54 strains (54/58, 93.10%) clustered to the Clade 1A.3a2, two strains (2/58, 3.45%) clustered to the Clade 1A.3a1, and two strains (2/58, 3.45%) in the same subgroup (Clade 1A.3) as the vaccine component BV strain in 2021-2022. Compared with the vaccine strain (B/Washington/02/2019), two BV strains had an additional N-glycosylation site at residue 197, while the other 56 strains showed no change in N-glycosylation sites. Antigenic analysis showed that 35 BV strains (35/58, 60.34%) were antigenically similar to the vaccine strain and 23 strains (23/58, 39.66%) were low-response strains.Conclusions:Three subgroups of BV viruses co-circulated in Beijing during the 2021-2022 influenza surveillance season. The predominant subgroup was Clade 1A.3a2 (93.10%), showing a certain genetic distance with the vaccine strain (B/Washington/02/2019). Nearly 40% (39.66%) of the viruses were low-response strains. This study indicated that continuous monitoring of the variations of influenza epidemic strains and timely providing laboratory basis for screening vaccine component strains were the basic technical guarantee for coping with influenza pandemic.

Objective To propose specific suggestions for exemption management of X-ray devices applying for exemption management. Methods The weight analysis of influence of shielding thickness and tube voltage on the radiation dose leakage of low-energy X-ray devices was carried out through test analysis, and the radiation status of 50 X-ray devices applied for end-user exemption in Shenzhen, China was investigated. Results There was no significant correlation between the ambient dose equivalent rate and the tube voltage and tube current of the X-ray device. The ambient dose equivalent rate of 50 X-ray devices was 0.16-1.20 μSv/h. Among them, 8 X-ray devices had radiation dose leakage, that is, the ambient dose equivalent rate was greater than 0.36 μSv/h; the ambient dose equivalent rate of one X-ray device was 1.2 μSv/h, exceeding exemption management requirements. Conclusion Applications for exemption management and filing of X-ray devices should be treated differently, and their own shielding effect and inherent safety have a greater impact on radiation safety, which should be focused on.

Objective:To analyze the genomic characteristics and variations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) derived from an outbreak in inbound flight in Aug, 2022 in Beijing, and provide reference data for disease prevention and control and risk assessment.Methods:Fifty respiratory tract specimens from all cases in this outbreak were collected. The digital PCR (ddPCR) was used to determine the viral loads of the specimens. The full genome of the viruses were sequenced by Next-generation sequencing. Then analuses were performed on the genetic identity, variations and phylogenesis.Results:The median of viral loads in all 50 samples were 5.57×10 4 copies/ml and 5.85×10 4 copies/ml, for ORF1ab gene and N gene, respectively. A total of 46 SARS-CoV-2 genomes were obtained, which all belonged to Omicron/BA.5. Two genome clusters were observed, involving 21 and 7 cases, with a nucleotide sequence identities of 99.993% and 99.997%, respectively. Conclusions:The studied outbreak was composed of two main clusters and other individual cases with Omicron/BA.5 virus overseas.

Objective To investigate the protective effect of adult human liver-derived stem cell exosomes (HLSC-exo) intravenously injected at different time points against acute liver injury induced by concanavalin A (ConA) in mice. Methods HLSC-exo was extracted by differential centrifugation. Western blot was used to measure the expression of the marker proteins CD9 and CD63, and nanoparticle tracking analysis was used to investigate particle size distribution. A total of 56 male C57BL/6 mice were randomly divided into blank control group, ConA model group, and HLSC-exo treatment group. The ConA model group and the HLSC-exo treatment group were further divided into 3-, 6-, and 12-hour subgroups according to the interval between phosphate buffer or HLSC-exo injection and ConA injection. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) were measured, and the gross morphology and histopathology of the liver were compared between groups. A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the least significant difference t -test was used for further comparison between two groups. Results HLSC-exo was a membranous vesicle with a diameter of 90-110 nm, with a clear saucer-like structure under an electron microscope and marked expression of its specific marker proteins CD9 and CD63. In the blank control group, the levels of ALT and AST were 31.81±6.74 U/L and 69.75±8.30 U/L, respectively. Compared with the blank control group, the 3-, 6-, and 12-hour ConA model groups had significant increases in the levels of ALT and AST (all P < 0.001); compared with the 3-and 6-hour ConA model groups, the 3-and 6-hour HLSC-exo treatment groups had significant reductions in the levels of ALT and AST (225.58±115.59 U/L vs 1989.32±347.67 U/L, 1174.71±203.30 U/L vs 2208.33±349.96 U/L, 303.53±126.68 U/L vs 2534.27±644.72 U/L, 1340.70±262.56 U/L vs 2437.13±288.13 U/L, all P < 0.001); compared with the 6-hour HLSC-exo treatment group, the 3-hour HLSC-exo treatment group had significantly greater reductions ( P < 0.001). In the blank group, the levels of IL-10 and TNF-α were 313.51±10.97 pg/ml and 476.05±7.31 pg/ml, respectively. Compared with the blank control group, the 3-, 6-, and 12-hour ConA model groups had a significant reduction in the level of IL-10 (all P < 0.001); compared with the 3-and 6-hour ConA model groups, the 3-and 6-hour HLSC-exo treatment groups had a significant increase in the level of IL-10(331.61±10.46 pg/ml vs 266.20±8.15 pg/ml, 288.13±10.74 pg/ml vs 264.41±9.12 pg/ml, both P < 0.001); compared with the 6-hour HLSC-exo treatment group, the 3-hour HLSC-exo treatment group had a significantly greater increase ( P < 0.001). Compared with the blank control group, the 3-, 6-, and 12-hour ConA model groups had a significant increase in the level of TNF-α (all P < 0.001); compared with the 3-and 6-hour ConA model groups, the 3-and 6-hour HLSC-exo treatment groups had a significant reduction in the level of TNF-α (478.26±12.99 pg/ml vs 551.31±17.70 pg/ml, 515.58±7.18 pg/ml vs 556.21±11.15 pg/ml, both P < 0.001); compared with the 6-hour HLSC-exo treatment group, the 3-hour HLSC-exo treatment group had a significantly greater reduction ( P < 0.001). Compared with the 3-and 6-hour ConA model groups in terms of the gross morphology and histopathology of the liver, the 3-and 6-hour HLSC-exo treatment groups had a significant reduction in the degree of hepatocyte necrosis, and the 3-hour HLSC-exo treatment group had a basically complete lobular structure, with sporadic spotty necrosis; the 12-hour HLSC-exo treatment group had no significant improvement in hepatocyte necrosis compared with the 12-hour ConA model group. Conclusion Intravenous injection of adult HLSC-exo can alleviate acute liver injury induced by ConA in mice, and injection at 3 hours in advance has the most significant protective effect. Regulation of cytokines is one of the important mechanisms for HLSC-exo to alleviate liver injury.

Objective:To establish a nested PCR method to detect the 2019 novel coronavirus (2019-nCoV), as a supplement to the real-time fluorescent PCR method, and discuss the preliminary application value of this method in clinical diagnosis.Methods:According to the conservative sequences of the 2019-nCoV gene, the nested PCR primers including N gene and S gene, were designed on line. By optimizing the nested PCR reaction systems, the qualitative detection was established by testing N gene and sequencing its PCR product while the preliminary type identification was established by testing S gene and sequencing its PCR product. The sensitivity was evaluated by the gradient dilution of 2019-nCoV positive samples’ nucleic acid and the specificity was evaluated by detecting the human coronavirus OC43, 229E, HKU1, NL63, influenza virus positive samples. The established method was applied to 15 samples with Ct >33 and 15 samples with Ct <33 screened by real-time fluorescent PCR, and the positive amplification result were sequenced and analyzed to verify the result. Results:The established nested PCR method could amplify specific bands of 355 bp N gene fragment and 449 bp S gene fragment. No amplifications occurred in other human coronaviruses samples including 229E、OC43、HKU1、NL63 or in influenza virus samples including H3N2, H1N1(pdm) and B. The minimum detection limit of the N gene fragment could reach Ct value about 37.21. Among the 30 COVID-19 positive samples, the N gene positive coincidence rate detected by nested PCR was 100% (30/30); the S gene positive coincidence rate reached 60% (18/30). 28 samples’ sequences of N gene fragment were completely consistent with 2019-nCoV by BLAST, and the characteristic result of site mutations of 12 samples’ S gene was obtained. Conclusions:A nested PCR method for the specific detection of 2019-nCoV was established, and some characteristic mutations on S gene could be analyzed by sequencing the PCR amplified products. It could be used as a supplement to the real-time fluorescent PCR method.

Objective To establish a new patient-derived xenograft (PDX) model of human liver cancer by inoculating the complex of human primary liver cancer cells and a novel microcarrier (microcarrier 6) into mice with normal immune function. Methods Primary liver cancer cells were isolated and extracted from the fresh human liver cancer tissue of five patients and were then co-cultured with microcarrier 6 to construct a three-dimensional tumor cell culture model in vitro . According to the type of graft, 75 male C57BL/6 mice were divided into cell control group, microcarrier control group, and experimental group (each sample corresponded to three groups, with 15 groups in total and 5 mice in each group). The liver cancer cell-microcarrier complex was implanted into the mice by subcutaneous inoculation, and tumor formation time, tumor formation rate, and histopathological manifestations were observed. The Fisher's exact test was used for comparison of categorical data between two groups. Results As for the liver cancer cells from the five patients, tumor formation was observed in the mice corresponding to three patients. In these three experiments, tumor formation was not observed in the control groups and was only observed in the experimental groups, and 12 of the 15 mice in the experimental groups had successful tumor formation, with a tumor formation rate as high as 80%, which was significantly different from that in the cell control groups and the microcarrier control groups (all P < 0.05). The tumor formation time was 5-7 days; the xenograft tumor grew rapidly, and HE staining showed nested or flaky cells with obvious heteromorphism, with the presence of pathological mitosis; immunohistochemical staining showed positive CK8/18, Hep, and Gpc-3, which was in accordance with the characteristics of human liver cancer cells. Conclusion This experiment successfully establishes a new PDX model of human liver cancer based on the complex of microcarrier 6 and human primary liver cancer cells in mice with normal immunity. This model can be used to better elucidate the mechanism of the development and progression of liver cancer in the body with normal immunity, and besides, it also provides a new animal model with higher value for the precise treatment of liver cancer.

Objective:Establishment of a new model of human primary colon cancer transplantation tumor in normal immune mice and to provide a reliable experimental animal model for studying the pathogenesis of colon cancer under normal immunity.Methods:Human colon cancer cells come from colon cancer patients who underwent surgery in the Affiliated Hospital of Jining Medical College in 2017. The mice in the cell control group were inoculated with phosphate buffered solution (PBS) containing colon cancer cells, the microcarrier control group was inoculated with PBS containing microcarrier 6, and the cell-microcarrier complex group was inoculated with the PBS containing colon cancer cell-microcarrier complex. The cells of each group were inoculated under the skin of the right axilla of mice by subcutaneous injection, and the time, size, tumor formation rate and pathological changes under microscope were recorded. The transplanted tumor tissue was immunohistochemically stained with the EnVisiion two-step method, and the tumor formation rate of the transplanted tumor was judged according to the proportion of positive cells in the visual field. The polymerase chain reaction (PCR) method was used to detect the expression of human-specific Alu sequence in mice tumor tissue.Results:After inoculation with tumor cells, the mice in the cell control group and the microcarrier control group did not die and did not form tumors; the mice in the cell-microcarrier complex group had palpable subcutaneous tumors in the right axillary subcutaneously on the 5th to 7th days after inoculation, and tumor formation rate is 67% (10/15), and the tumor volume can reach about 500 mm 3 2 to 3 weeks after vaccination. The immunohistochemistry results showed that CK20, CDX-2 and carcinoembryonic antigen were all positively expressed. The PCR results showed that the expression of human-specific Alu sequence can be detected in the transplanted tumor tissue of tumor-bearing mice. Conclusion:Human primary colon cancer cells used microcarrier 6 as a carrier to form tumors in normal immunized mice, and successfully established a new model of human colon cancer transplantation tumor in normal immune mice.

Objective:Establishment of a new model of human primary colon cancer transplantation tumor in normal immune mice and to provide a reliable experimental animal model for studying the pathogenesis of colon cancer under normal immunity.Methods:Human colon cancer cells come from colon cancer patients who underwent surgery in the Affiliated Hospital of Jining Medical College in 2017. The mice in the cell control group were inoculated with phosphate buffered solution (PBS) containing colon cancer cells, the microcarrier control group was inoculated with PBS containing microcarrier 6, and the cell-microcarrier complex group was inoculated with the PBS containing colon cancer cell-microcarrier complex. The cells of each group were inoculated under the skin of the right axilla of mice by subcutaneous injection, and the time, size, tumor formation rate and pathological changes under microscope were recorded. The transplanted tumor tissue was immunohistochemically stained with the EnVisiion two-step method, and the tumor formation rate of the transplanted tumor was judged according to the proportion of positive cells in the visual field. The polymerase chain reaction (PCR) method was used to detect the expression of human-specific Alu sequence in mice tumor tissue.Results:After inoculation with tumor cells, the mice in the cell control group and the microcarrier control group did not die and did not form tumors; the mice in the cell-microcarrier complex group had palpable subcutaneous tumors in the right axillary subcutaneously on the 5th to 7th days after inoculation, and tumor formation rate is 67% (10/15), and the tumor volume can reach about 500 mm 3 2 to 3 weeks after vaccination. The immunohistochemistry results showed that CK20, CDX-2 and carcinoembryonic antigen were all positively expressed. The PCR results showed that the expression of human-specific Alu sequence can be detected in the transplanted tumor tissue of tumor-bearing mice. Conclusion:Human primary colon cancer cells used microcarrier 6 as a carrier to form tumors in normal immunized mice, and successfully established a new model of human colon cancer transplantation tumor in normal immune mice.

Objective:To establish a mouse model of gastric cancer by inoculating MKN45 cells into mice with normal immune function utilizing microcarrier technology. Methods:A total of 60 male C57BL/6 mice were randomly divided into three groups, namely, 2D, con-trol, and 3D groups, according to the coculture system of MKN45 and microcarrier. The mouse models of gastric carcinoma were estab-lished by hypodermic injection. The time of tumorigenesis, rate of tumor formation, and pathological features were observed in each group. Results:In the 3D group, the time of tumor formation was short, whereas the rate of tumor formation was high (80%). No de-tectable tumor formations were observed in the 2D and control groups. HE and immunohistochemical staining of the transplantation tumor model showed evident characteristics of human gastric cancer. Conclusion:A human gastric cancer model in normal immune mice was successfully established. The onset and development mechanism of gastric cancer could be more effectively investigated in mice with normal immune function through this model. Moreover, a more valuable and new animal model for the research and devel-opment of anticancer drug was established.

Objective: To investigate the protective effect of intraperitoneal transplantation of human liver-derived stem cells at different times against concanavalin A (ConA)-induced acute liver injury in mice. Methods: A total of 88 male C57BL/6 mice were randomly divided into normal control group (group C), ConA model group (group M), and human liver-derived stem cells (HYX1)+ConA group (group E); according to the interval between phosphate buffer/HYX1 injection and ConA injection, Groups M and E were further divided into 3-hour groups (M1 and E1 groups), 6-hour groups (M2 and E2 groups), 12-hour groups (M3 and E3 groups), 24-hour groups (M4 and E4 groups), and 48-hour groups (M5 and E5 groups). The levels of alanine aminotransferase (ALT), aspartate transaminase (AST), and total bilirubin (TBil) in peripheral blood were measured, liver tissue sections were used to observe pathological changes, and the Ishak score for liver inflammation was determined. The independent samples t-test was used for comparison between groups, and P < 0.05 was considered statistically significant. Results: The levels of ALT, AST, and TBil in group C were (36.25±1.16) U/L, (120.20±5.77) U/L, and (2.20±0.23) μmol/L, respectively; the levels of ALT, AST, and TBil and Ishak score were (8 721.23±837.39) U/L, (8 110.31±290.10) U/L, (8.41±0.10) μmol/L, and (13.32±1.30), respectively, in group M1, (8 334.31±666.50) U/L, (7 560.20±760.34) U/L, (10.40±0.80) μmol/L, and (12.67±0.81), respectively, in group M2, (8 960.75±551.93) U/L, (8 535.62±675.14) U/L, (10.95±1.43) μmol/L, and (14.57±0.65), respectively, in group M3, (8 618.57±886.40) U/L, (11 440.54 ± 1 327.86) U/L, (13.30±1.86) μmol/L, and (13.21±1.06), respectively, in group M4, and (10 170.13±1 112.37) U/L, (11 470.56±1 108.40) U/L, (12.75±1.55) μmol/L, and (15.07±1.58), respectively, in group M5. The levels of ALT, AST, and TBil and Ishak score were (1 016.35±163.47) U/L, (952.30±103.91) U/L, (7.77±0.62) μmol/L, and (3.50±0.21), respectively, in group E1, (42.10±6.20) U/L, (126.72±13.33) U/L, (3.41±0.53) μmol/L, and (2.01±0.40), respectively, in group E2, (44.21±4.30) U/L, (216.71±35.88) U/L, (3.47±0.44) μmol/L, and (2.13±0.25), respectively, in group E3, (2 909.69±212.14) U/L, (2 988.43±333.70) U/L, (7.03±0.93) μmol/L, and (4.70±0.50), respectively, in group E4, and (7 874.26±799.60) U/L, (10 940.54±947.35) U/L, (10.53±1.09) μmol/L, and (8.60±0.83), respectively, in group E5. Groups M1-M5 had significantly higher levels of ALT, AST, and TBil than group C (all P < 0.01), and groups M1-M4 had significantly higher levels of AST and ALT than groups E1-E4 (all P < 0.01), while there were no significant differences in the levels of AST and ALT between groups M5 and E5 (both P > 0.05). The pathological sections of liver tissue showed that compared with group M, group E had significant reductions in the degree of necrosis and Ishak score (both P < 0.05). Conclusion Intraperitoneal transplantation of human liver-derived stem cells has a protective effect against ConA-induced acute liver injury in mice, and the injection at 6 and 12 hours in advance has the best protective effect.