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Group Ⅱ introns are self-splicing ribozymes, which insert directly into target sites in DNA with high frequency through "retrohoming". They specifically and efficiently recognize and splice DNA target sites, endowing themselves with great potential in genetic engineering. This paper reviewed the gene targeting principle of group Ⅱ introns and the application in microbial genetic modification, and then analyzed the limitations of them in multi-functional gene editing and eukaryotes based on the "retrohoming" characteristics and the dependence on high Mg2+ concentration. Finally, we dissected the potential of group Ⅱ introns in the development of novel gene editing tools based on our previous research outcome and the structural characteristics of the introns, hoping to provide a reference for the application of group Ⅱ introns in biotechnology.
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DNA , Eucariotos , Marcação de Genes , Íntrons/genética , RNA Catalítico/genéticaRESUMO
Objective:To explore the differences in intravascular ultrasound results in elderly coronary heart disease(CHD)patients with different uric acid levels.Methods:A total of 145 elderly patients diagnosed with CHD in our hospital from December 2017 to May 2020 were included as study subjects.Uric acid levels were measured and intravascular ultrasound examination was conducted in all patients.They were divided into different groups based on uric acid levels: Group A(uric acid≤199 μmol/L), Group B(uric acid 200~399 μmol/L)and Group C(uric acid≥400 μmol/L). Data from intravascular ultrasound-derived indexes were analyzed and compared between the three groups.Results:There was no significant difference in the degree of left main stenosis between Group A and Group B, but it was less severe in both groups than in Group C( F=5.625, P=0.039). Plaque fibrous cap thickness showed no significant difference between Group B and Group C, but it was smaller than in Group A( F=7.825, P=0.020). Group C had the largest plaque area and maximum thickness among the three groups, followed by Group B[(11.12±1.73)mm 2 and(1.76±0.24)mm]and Group A[(8.29±3.14)mm 2 and(1.38±0.09)mm]( F=6.384 and 6.827, P=0.028 and 0.015). Conclusions:Elevated uric acid levels in elderly CHD patients can increase the area and thickness of plaques, and reduce plaque fibrous cap thickness, leading to an increased risk of formation of unstable plaques, which can be life-threatening for these patients.Thus, monitoring and managing uric acid levels should be stressed in elderly CHD patients.
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Objective@#To investigate the action and antioxidant effects of CB2 agonist AM-1241 on rat hepatic stellate cell line (HSC-T6).@*Methods@#HSC-T6 was randomly divided into four groups: control group, oxidative stress group, AM-1241 intervention group and AM-1241+AM-630 antagonist group. Survival rate of HSC-T6 was detected by thiazolyl blue assay under 24 h interventions with 0, 20, 50, 80 μmol/L AM-1241 and 0, 10, 20, 30, 40 μmol/L AM-630, respectively. Besides control group, the remaining groups were well cultured in low-glucose DMEM containing 100 mU/L glucose oxidase (GO) for 12 h to prepare the oxidative stress model. Then, AM-1241 intervention group was treated with 50 μmol/L low-glucose DMEM medium. After incubation for 12 h, the AM-1241+AM-630 antagonist group was treated with CB2 antagonist AM-630 (20 μmol/L) for 2 h, and cultured with 50 μmol/L AM-1241 in complete low-glucose medium for 12 h. The optimal drug concentration was selected according to the cell viability considered by the experiment results. Type III collagen (C III) content in the HSC-T6 supernatant was detected by enzyme-linked immunosorbent assay. Glutathione (GSH) content in HSC-T6 was detected by spectrophotometry. CB2 and heme oxygenase-1(HO-1) in each group of HSC-T6 were detected by western blotting.@*Results@#HSC-T6 proliferation was inhibited in each group of AM-1241 in a concentration-dependent manner (P < 0.05). The inhibition was highest at 80μmol/L, and the cell survival rate was (41.61% ± 3.13%) (P < 0.05). AM-630 concentration group had no significant inhibitory effect on the proliferation of HSC-T6 (P > 0.05). HSC-T6 expressed CB2 receptor in each group. The expression level of CB2 in the AM-1241 intervention group was higher compare with control group (P < 0.05).The expression of Col III were significantly higher in oxidative stress group (P < 0.05) than in control group, and the expression of Col III of AM-1241 intervention group was significantly lower than that in oxidative stress group (P < 0.05). Col III level in AM-1241+AM-630 antagonistic group was significantly higher than that in AM-1241 intervention group (P < 0.05). There was no significant difference between AM-1241+AM-630 antagonistic group and oxidative stress group (P > 0.05). The content of GSH and HO-1 in oxidative stress group was higher (P < 0.05) than control group. The content of GSH and HO-1 in the AM-1241 intervention group was higher compared with oxidative stress group, while content of AM-1241 + AM-630 antagonist group was lower compared to AM-1241 intervention group (P < 0.05), and the differences were not statistically significant for oxidative stress group.@*Conclusion@#CB2 agonist AM-1241 can inhibit the proliferation and activation of HSC-T6 and its mechanism may activate the nuclear translocation of Nrf2 binding to HSC-T6, initiating the up-regulation of antioxidant enzymes HO-1 and GSH protein expression, and thus increase the antioxidant effect of HSC-T6.
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Objective To investigate the feasibility of subtraction coronary computed tomography angiography (Sub-CCTA) for the diagnosis of coronary heart disease in the segment with severe calcification.Methods A retrospective analysis was performed on 27 patients who underwent clinically indicated digital subtraction angiography (DSA) and CCTA using a 320-detector row CT.Compared with the results of DSA,sensitivity,specificity,positive predictive value,negative predictive value and accuracy of Con-CCTA and Sub-CCTA were calculated.The clinical diagnostic accuracy of the two imaging methods was evaluated using the receiver operating characteristic (ROC) curve.The stenosis of coronary segments was divided into four grades (Ⅰ,Ⅱ,Ⅲ,Ⅳ).Kappa coefficient was used to measure agreement between two imaging methods.Image quality of 4-scale grade scoring method was used and t test was conducted.Results A total of 52 segments with severe calcification were evaluated.The scores of image quality in Con-CCTA and Sub-CCTA were 2.8 ± 0.5 and 3.4 ± 0.7,respectively.There was significant difference between them (t =5.9,P ＜ 0.05).Compared with the result of DSA as the golden standard,the Kappa coefficients were 0.55 and 0.81 respectively in Con-CCTA and Sub-CCTA for the quantitative evaluation of the severe calcified segments.The sensitivity,specificity,positive predictive value and negative predictive value and accuracy of Con-CCTA were 81.0％,63.1％,63.1％,81.1％ and 70.8 ％;and for Sub-CCTA they were 90.5 ％,85.2％,82.1 ％,92.0％ and 87.5 ％ respectively.Compared with Con-CCTA,the area under the ROC curve of Con-CCTA and Sub-CCTA were 0.84 (95％CI:0.70-0.93) and 0.96 (95％ CI:0.86-1.00),respectively,and the difference was statistically significant (P =0.03).Conclusions Sub-CCTA can improve the diagnostic accuracy of coronary artery stenosis in severe calcified segment.Application of subtraction technique in CCTA can reduce or even eliminate the artifacts caused by severe calcified plaque,and has a good clinical application prospect.
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Objective To evaluate the efficacy of narrow-band ultraviolet B (NB-UVB) for the treatment of early-stage mycosis fungoides (MF).Methods A retrospective study was performed on 98 patients with early-stage MF treated with NB-UVB from January 2003 to December 2013.The rate of and time to recurrence of MF were assessed,and long-term side effects were evaluated in these patients.Results Among 52 patients achieving complete remission,the median number of sessions of NB-UVB radiation was 30 (range,18-87),the median cumulative radiation dose was 24.16 J/cm2 (range,9.11-108.86 J/cm2),and the median follow-up duration was 41 months (range,11-90 months).Relapse occurred in 14 (26.9％) patients with the median time to recurrence being 8.2 months (range,3-60 months).The patients suffering from relapse achieved complete remission after treatment with NB-UVB again.Adverse reactions mainly included skin erythema and itching at the early stage of radiation,as well as temporary pigmentation after radiation.Cutaneous carcinoma occurred in none of these patients during 11-90 months of follow-up.Conclusions NB-UVB phototherapy appeared to be effective for the treatment of early-stage MF,and no cutaneous carcinoma occurred in these patients during the follow-up.Although MF may relapse in some cases,repeated NB-UVB phototherapy is still effective.
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Objective To investigate changes in expressions of activation antigens CD69 and HLA-DR in CD3+T lymphocytes in peripheral blood and skin lesions in patients with psoriasis vulgaris. Methods Peripheral blood samples were obtained from 20 patients with psoriasis vulgaris and 20 healthy controls, and skin specimens from the lesions of 15 out of the 20 patients and 10 healthy controls. Flow cytometry was performed to quantify the expressions of CD69 and HLA-DR in peripheral blood CD3+T cells, and an immunohistochemical study to measure the expression of HLA-DR in skin specimens. Statistical analysis was carried out by a two-sample t-test and Pearson correlation analysis with the SPSS 19.0 software. Results Compared with the healthy controls, the patients with psoriasis vulgaris showed increased expression rates of CD69 (4.70%± 1.90%vs. 1.56%± 0.95%, t=6.629, P<0.01)and HLA-DR (8.97%± 1.79% vs. 3.02% ± 1.15%, t= 6.204, P< 0.01)in peripheral blood. Pearson correlation analysis revealed that the percentage of CD3+HLA-DR+cells in peripheral blood was positively correlated with the psoriasis area and severity index (PASI)score (r=0.5626, P<0.05). The expression rate of HLA-DR was significantly higher in the dermis (64.87%± 17.31%vs. 19.80%± 5.69%, t=7.916, P<0.01), but lower in the epidermis(11.80%± 5.55%vs. 27.40%± 8.61%, t=5.479, P<0.01)in the psoriatic specimens compared with the control specimens. Immunohistochemically, HLA-DR was widely expressed in the dermis of psoriatic lesions, but mainly distributed around blood vessels in the control skin. Conclusions There is an aberrant activation of CD3+T cells in peripheral blood and inflammatory cells in skin lesions in patients with psoriasis vulgaris, and the percentage of CD3 +HLA-DR+ cells in peripheral blood is correlated with the severity of psoriasis vulagaris.