Objective To construct replication-defective adenovirus containing tk gene (ADV-tk). Methods Recombinant adenovirus of ADV-tk was constructed using homologous recombination in cells. After the interested tk gene fragment in the recombinant plasmid obtained was confirmed by PCR, the titre of purified recombinant adenovirus was detected. In vitro study, tk gene in SMMC7721 cells transfected by ADV-tk was investigated by RT-PCR. In vivo study, ADV-tk was injected intraperitoneally into BALB/c nude mice with liver cancer and apoptosis cells in tumor were observed. Results Recombinant adenovirus containing ADV-tk was proved successfully. The titre of purified recombinant adenovirus was 1.4×1010 pfu/ml. In vitro study, tk was integrated and expressed by SMMC-7721 cells. In vivo study, with the injection of ADV-tk, apoptosis cells in tumor increased. Conclusion A replication-defective adenovirus containing tk gene is successfully constructed, which may useful for further research on tumor suicide gene therapy with ADV-tk.
Objective To design and construct the eukaryotic expressed vector of suicide genes, which contained 5 copies of hypoxia-responsive element (5HRE), promoter of alpha-fetoprotein gene (AFPp） and nitroreductase from Escherichia coli. Methods The constructing processes were as follows: ①The design of primer: Suicide genes of NTR in the Escherichia coli, which contained 6his-tag gene (6his-tag), were cloned by overlapping PCR. ②The construction of 5HRE: The single strand of synthetized HRE oligonucleotide was annealed, and 5HRE was constructed by multiple recombinant clone. ③The recombination of NTR gene, 5HRE, AFPp and pIRES2-EGFP: pIRES2-EGFP, which had removed the instant early promoter of cytomegalovirus, was recombined with NTR gene, 5HRE, AFPp. In this way, the eukaryotic expressed vector of pIRES2-EGFP-5HRE-AFPp-NTR, which carried NTR gene, 5HRE, AFPp was finally constructed. Results NTR gene, which contained the fusion of 684-base pair and 6his-tag gene, was cloned successfully, and its sequence was coincident with the result published by Genbank. A 221-base pair of 5HRE was also constructed, which was in accordance with the expected sequences. The integrity of the eukaryotic expressed vector was verified by restriction enzyme digestion and DNA sequence analysis, respectively. Conclusion The eukaryotic expressed vector of pIRES2-EGFP-5HRE-AFPp-NTR is successfully constructed, which may be used for its further investigation in vitro.
ObjectiveTo systematically evaluate the correlation between interpersonal stress and suicidal ideation. MethodsThe PubMed, EMbase, Cochrane Library, CBM, WanFang Data and CNKI databases were searched to collect studies on the correlation between interpersonal pressure and suicidal ideation from database inception to April 27, 2022. Two researchers independently screened the literature, extracted data and assessed the risk of bias of the included studies. Meta-analysis was then performed using Stata 14.0 software. ResultsA total of 42 studies including 3 cohort studies, and 39 cross-sectional studies, with a total sample size of 193 810 participants were included. Meta-analysis showed that the risk of suicidal ideation was higher in people who had experienced interpersonal pressure than in people who had not (OR=2.11, 95%CI 1.99 to 2.23, P<0.01). Subgroup analysis showed that people in the Americas who had experienced interpersonal pressure were more strongly associated with suicidal ideation than people in other regions of the studied area. Young adults in the study who had experienced interpersonal pressure were more strongly associated with suicidal ideation than other studied age groups; People who had experienced partner pressure were more strongly associated with suicidal ideation than those who had experienced other types of interpersonal pressure. ConclusionThis study shows that people who have experienced interpersonal pressure are at greater risk of suicidal ideation, and there are certain differences among study areas, subjects and types of interpersonal pressure. Due to the limited quantity and quality of the included studies, more high-quality studies are needed to verify the above conclusion.
Objective To observe the influence of connexin 43 (Cx43) on bystander effects induced by cytosine deaminase (CD) and herpes simplex virus thymidine kinase (HSV-tk) coexpression suicide genes system in human cholangiocarcinoma QBC939 cells and transplantation tumors in nude mice. Methods In vitro, the CD+tk+ and CD+tk+Cx+ cells were respectively treated with 5-fluorocytosine (5-FC) and ganciclovir (GCV). The cytotoxic efficacy was evaluated by microculture tetrajolium test (MTT) method. In order to investigate the influence of Cx43 on bystander effects, the volumes of transplantation tumors of the CD+tk+ and CD+tk+Cx+ cells were measured before and after application of 5-FC and GCV. Results CD and tk gene were stably expressed in transfected QBC939 cells. Increasing expression of Cx43 was determined by testing for the presence of Cx43 mRNA by RT-PCR and the presence of Cx43 protein by Western blot in CD+tk+Cx+ cells. The killing effect of 5-FC and GCV on CD+tk+Cx+ cells was more effective than that on CD+tk+ cells both in vitro and in vivo. Conclusion Double suicide genes system CD/5-FC+tk/GCV could induce remarkable killing effect on cholangiocarcinoma cells in vitro and transplantation tumors in vivo. The cotransfection of Cx43 gene is able to enhance the bystander effects and the inhibition of carcinoma cells.
Objective To systematically review injury, death, and their causes in elderly people in China from 2000 to 2020 and to prevent and reduce the occurrence of injuries and death. Methods The CNKI, VIP, WanFang Data, PubMed, SinoMed, and Web of Science databases were searched to collect studies on injury and death among elderly people over 60 years of age who resided in China from January 2000 to December 2020. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias of the included studies. A meta-analysis was then performed using R 4.1.2 software. Results A total of 41 studies with 187 488 subjects were included, including 125 million elderly individuals. The pooled injury mortality rate was 135.58/105 (95%CI 113.36/105 to 162.14/105, P<0.001). Subgroup analysis showed that male injury death (146.00/105, 95%CI 116.00 to 183.74, P=0.001) was significantly higher than that of females (127.90/105, 95%CI 102.31 to 159.88, P=0.001) and that overall injury mortality increased exponentially with age (R2=0.957), especially in those over 80 years old. The spatial distribution showed that the injury death rate in the central region was higher than that in the east and west and higher in the countryside than in the city. The time of death distribution showed that after China became an aging society (2000-2020), the time of death was significantly later than before (1990-2000). There were more than 12 types of injuries that caused death, the top three of which were falling, traffic accidents, and suicide. Conclusion From 2000 to 2020, the injury mortality rate of the elderly people in China initially increase and then slightly decrease. The phenomenon affects more men than women, especially those beyond the age of 80. Regional differences are identified, and the types of injuries that cause death are mainly falls, traffic accidents, and suicide. Due to the limited quantity and quality of the included studies, more high-quality studies are needed to verify the above conclusion.
Objective To estimate the incidence of suicidal ideation of Chinese medical students in mainland China over the past ten years by meta-analysis, so as to provide references for suicide prevention and mental health education in Chinese medical students. Methods PubMed, CNKI, WanFang Data and CBM databases were searched for studies investigating the prevalence of suicidal ideation among Chinese medical students in mainland China from January 1st, 2007 to 31st May, 2017. After study selection according to inclusion and exclusion criterion, data extraction and quality assessment, meta-analysis was conducted using Stata 12.0 software. Heterogeneity was evaluated by performing subgroup analyses and meta-regression. We also used sensitivity analysis to determine the influence of individual studies on the overall prevalence estimates. Results A total of 30 studies with 58 757 participants were included, the individual-study incidence of suicidal ideation ranged from 0.84% to 41.35%, with significant between-study heterogeneity detected (I2=99.1%, P<0.001), and the pooled incidence by random-effects model was 12.51% with 95%CI 9.72% to 15.60%. Univariate and multivariate meta-regression revealed that instruments were related to heterogeneity (P<0.01), but other study-level covariates did not contribute to heterogeneity (P>0.1). Conclusion The incidence of suicidal ideation among medical students in mainland China is relatively high, calling more attention to this concern and actions in response for suicide prevention and mental health education in Chinese medical students.