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BACKGROUND: The risk factors for complete atrioventricular block (CAVB) after device closure of perimembranous ventricular septal defect (pmVSD) remain unclear. OBJECTIVE: The purpose of this study was to analyze the incidence and risk factors for CAVB after device closure for pmVSD. METHODS: We reviewed 1884 patients with pmVSD who had undergone successful device occlusion between June 2005 and January 2020. Permanent CAVB was defined as CAVB requiring implantation of a permanent pacemaker (PPM) or extraction of the occluder. RESULTS: In total, 14 patients (0.7%) developed permanent CAVB. Of these patients, 10 (0.5%) required PPM implantation. Four permanent CAVB occurred within 7 days after the procedure (acute), 2 between 7 and 30 days (subacute), 3 between 30 days and 1 year (late), and 5 more than 1 year (very late). None of the subacute, late, and very late CAVB recovered normal conduction with medication and eventually required device removal or PPM implantation. Four patients with acute CAVB and 1 with subacute CAVB underwent device removal, and 4 (80%) recovered normal conduction. Multivariate regression revealed that the ratio of device to defect size was the only independent risk factor for permanent CAVB (odds ratio 3.027; 95% confidence interval 1.476-6.209; P = .003). CONCLUSION: The incidences of permanent CAVB after occlusion for pmVSD and PPM implantation were 0.7% and 0.5%, respectively. The ratio of device to defect size was the only independent risk factor for permanent CAVB. Device removal is an effective therapeutic modality for recovering normal conduction in acute and subacute CAVB patients.

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Seeds of higher plants accumulate numerous storage proteins to use as nitrogen resources for early plant development. Seed storage proteins (SSPs) are synthesized as large precursors on the rough endoplasmic reticulum (rER), and are delivered to protein storage vacuoles (PSVs) via vesicle transport, where they are processed to mature forms. We previously identified an Arabidopsis ER-localized tethering complex, MAG2 complex, which might be involved in Golgi to ER retrograde transport. The MAG2 complex is composed of 4 subunits, MAG2, MIP1, MIP2, and MIP3. Mutants with defective alleles for these subunits accumulated SSP precursors inside the ER lumen. Here, we report that the mag2-1 mip3-1 and mip2-1 mip3-1 double mutant have more serious vesicle transport defects than the mag2-1, mip2-1, and mip3-1 single mutants, since they accumulate more SSP precursors than the corresponding single mutants, and ER stress is more severe than the single mutants. The mag2-1 mip3-1 and mip2-1 mip3-1 double mutants show growth and developmental defects rather than the single mutants. Both single and double mutant seeds are found to have lower protein content and decreased germinating vigor than wild type seeds. All the mutants are sensitive to abscisic acid (ABA) and salt stress, and exhibit alteration in ABA signaling pathway. Our study clarified that ER-Golgi vesicle transport affects seed vigor through controlling seed protein quality and content, as well as plant response to environmental stress via influencing ABA signaling pathway.

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OBJECTIVE: To investigate the relationship of DNA methyltransferase 1 ( DNMT1 ) with hematopoietic cell phosphatase (SHP-1) gene expression and promoter 2 methylation status in cell line K562. METHODS: The promoter sequence of SHP-1 gene promoter 2 in NCBI database was analyzed, the K562 cells were transfected with the lentiviral plasmids-the specified retroviral vector psiHIV-mU6-shDNMT1 and psiHIV-mU6-mcherryFP-control. The methylation status of SHP-1 gene promoter 2 in K562 cells was detected by methylation-specific polymerase chain reaction (MSP) and bisulfite-modified sequencing (BSP). Western blot was used to detect the protein expression level of SHP-1 and DNMT1, the SYBR Green fluorescence quantitative PCR was used to detect the expression of SHP-1 mRNA. RESULTS: It was found that the promoter 2 of SHP-1 gene located between -577 bp to +300 bp, and 22 CpG sites contained between -353 bp-+182 bp were aberrantly hypermethylated and the SHP-1 could not be detected in K562 cells. In vitro, the detection demonstrated that the expression level of DNMT1 in K562 cells transfected with psiHIV-mU6-shDNMT1 was 0.48±0.06 significantly lower than that of psiHIV-mU6-control group (1.33±0.19)(t= 4.18, P<0.05). The expression of SHP-1 mRNA in K562 cells transfected with psiHIV-mU6-shDNMT1 was significantly higher than that in K562 cells transfected with psiHIV-mU6-shDNMT1 (14.23±3.83 vs 1.031±0.156)(P<0.01). DNMT1 silencing induced demethylation of the 22 CpG sites located in the SHP-1 promoter 2, and SHP-1 gene was re-expression in K562 cells. CONCLUSION: The DNMT1 in K562 cells relates with the hypermethylation and silencing of SHP-1 promoter in K562 cells.

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OBJECTIVE: To explore the effect of overexpression of SH2-containing tyrosine phosphatase 1 (SHP-1) on sensitivity of chronic myelogenous 1eukemia (CML) K562 cell line to imatinib and its related mechamism. METHODS: K562 cells were infected with the lentiviral plasmids containing the specified retroviral vector (pEX-SHP-1-puro-Lv105) or the mock vector (pEX-EGFP-puro-Lv105). The expression of SHP-1 in K562 cells treated with 0.2 µmol/L imatinib (IM) for 72 h was determined by Western blot. After transfection the CCK-8 assay was used to determine the proliferation of the tramfected K562 cells (K562(SHP-1) and K562(EGFP) cells) at 72 h after exposure to different doses of IM, the half inhibitary concentration (IC50) was calculated. The mechanisms of the overexpression effects of SHP-1 and IM on the proliferation in K562 cells was investigated, the BCR-ABL1 activity and the level of tyrosine phosphorylation of CrkL (pCrkL) was measured by flow cytometry; the Western blot was used to detect the expression and activity of these molecules controlling cell growth, including MAPK, AKT, STAT5 and JAK2. RESULTS: After exposure of K562 cells to 0.08 µmol/L IM for 72 h, there was no significant change of SHP-1 expression in K562 cells. After exposure to 0.2 µmol/L of IM for 72 h, the inhibitory rate of K562(SHP-1) group was higher than that of K562(EGFP) group (P < 0.05), indicating that overexpression of SHP-1 in K562 cells could enhance the proliferation inhtibition effect of IM on K562 cells. The IC50 of IM in K562(SHP-1) cells was the lower as compared with that of K562(EGFP) cells (P < 0.05) after exposure to different concentrations of IM for 72 h. The slope of K562(SHP-1) cells was the largest ranging 0.02 - 0.16 µmol/L of IM. Overexpression of SHP-1 and IM could inhibit the activity BCR-ABL1, MAPK, AKT, STAT5 and JAK2 signaling pathways in the K562 cell line and displayed a synergistic effect. CONCLUSION: SHP-1 inhibits BCR-ABL1, MAPK, AKT, STAT5 and JAK2 signaling pathways in K562 cells, the overexpression of SHP-1 can enhance the sensitivity of K562 cells to IM.

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OBJECTIVE: To investigate the expression and clinical significance of DNA methyltransferases (DNMT) mRNA in patients with chronic myeloid leukemia (CML). METHODS: The expression levels of DNMT mRNA in mononucllear cells (MNC) of bone marrow or in peripheral blood of 93 CML patients in 3 different phases and 10 normal controls (NC) were detected by SYBR Green flurescent quatitative PCR. RESULTS: The relative expression levels of DNMT1 mRNA in NC, chronic phase CML (CML-CP), accelerated phase (CML-AP) and blastic phase (CML-BP) were 1.45 ± 0.22, 1.83 ± 0.63, 2.95 ± 0.87 and 3.24 ± 1.39 resectively. The expression of DNMT1 mRNA showed no statistically significant difference between CML-CP and NC (P = 0.28). The expression of DNMT1 mRNA in advanced stages (including CML-AP and CML-BP) of CML obviously increased in comparison with CML-CP and NC (P < 0.05). The expression of DNMT1 mRNA in CML-AP was not significantly different from that in CML-BP (P = 0.336). The relative expression levels of DNMT3a mRNA in NC, CML-CP, CML-AP and CML-BP groups were 1.29 ± 0.34, 1.34 ± 0.46, 2.33 ± 1.05 and 3.18 ± 1.23 resectively. And the expression levels of DNMT3a mRNA were not statistically significantly different between CML-CP and NC (P = 0.844). The results showed that the expression of DNMT3a mRNA in the advanced phase of CML significantly increased in comparison with that in CML-CP and NC (P < 0.05). Meanwhile, the expression of DNMT3a mRNA in CML-AP was not different from that in CML-BP (P = 0.304). The relative expression levels of DNMT3b mRNA in NC, CML-CP, CML-AP and CML-BP groups were 1.37 ± 0.31, 16.41 ± 22.50, 9.36 ± 5.50 and 12.17 ± 13.44 resectively. It was also found that the level of DNMT3b mRNA in CML significantly increased in comparison with NC (P < 0.05), and that the between the 3 different phase of CML was not statistically significantly different (P >0.05). CONCLUSION: The expression of DNMT mRNA increases in advanced CML as compared with normal controls and CML-CP, and the increased levels of DNMT mRNA probably correlate with disease progression in CML.

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