ObjectiveTo study the synergistic effect of p38MAPK and ERK1/2 in bone marrow mesenchymal stem cells (BMSCs), and to explore their influence on osteogenic differentiation in BMSCs cultures. MethodsMouse BMSCs were cultured in phenol red-free α-MEM containing osteogenic supplements (OS) for inducing osteogenic differentiation. The temporal sequence of osteogenic differentiation in BMSCs cultures was assayed by measuring alkaline phosphatase activity (ALP) and calcium deposition gene expression. The activation of p38MAPK and ERK1/2 was detected by western blotting using phospho-specific MAP kinase antibody. BMSCs were treated with the inhibitor of p38MAPK pathway(SB203580) or ERK1/2 pathway (PD98059), and osteogenic differentiation was measured. BMSCs were treated with SB203580 or sodium arsenite(ARS), a strong activator of p38MAPK, and the phosphorylation of ERK 1/2 was measured. BMSCs were treated with PP2A inhibitor, Okadaic acid(OA), the phosphorylation of ERK1/2 and osteogenic differentiation were measured. lmmunoprecipitation was used to test the binding interaction between PP2A and ERK1/2, and the effect of SB203580 on the interaction. ResultsTreatment of BMSCs with osteogenic supplements resulted in activation of p38MAPK and ERK1/2 that coincided with osteogenic differentiation. Inhibition of p38MAPK activation by SB203580, blocked the osteogenic differentiation, whereas inhibition of ERK1/2 activation by PD98059, enhanced the osteogenic differentiation in a dose-dependent manner.SB203580 treatment resulted in increased ERK1/2 phosphorylation. By contrast, ARS treatment resulted in decreased ERK1/2 phosphorylation. Inhibition of PP2A by OA resulted in increased ERK1/2 phosphorylation. OS-induced osteogenic differentiation was also attenuated by PP2A inhibition. Immunoprecipitation confirmed the association of PP2A with ERK1/2 in BMSCs cultures, which was decreased by SB203580 treatment. ConclusionThe present study demonstrates a synergistic effect between p38MAPK and ERK1/2 signaling pathways via PP2A in BMSCs cultures, which may regulate the osteogenic differentiation of BMSCs.

Objective: To investigate the regulation of curculigoside on osteogenic differentiation of MG63 and the protective effect on osteoporosis model mice. Methods: The effects of curculigoside on the survival rate of dexamethasone or H₂O₂ treated MG63 were detected by methyl thiazolyl tetrazolium (MTT). The specimens were divided into six groups: blank control group, blank administration group, model group (dexamethasone or H₂O₂ treatment group), low dose group (dexamethasone or H₂O₂+1.0 μmol/L curculigoside), medium dose group (dexamethasone or H₂O₂+2.5 μmol/L curculigoside) and high dose group (dexamethasone or H₂O₂+5.0 μmol/L curculigoside), the sample size of each group was 10. Western blotting was used to detect the expression of osteogenic differentiation-related proteins [type Ⅰ collagen, integrin β1, osteoblast-specific transcription factor (Osterix), osteocalcin and osteopontin] in MG63 cells after 1, 7 and 14 days incubated with 0, 1.0, 2.5 and 5.0 μmol/L of curculigoside. The sample size for each group at each time point was six. The experimental mice were divided into 4 groups: blank group, model group (dexamethasone treatment group), curculigoside low-dose group (dexamethasone+5 mg/kg curculigoside) and high-dose group (dexamethasone+45 mg/kg curculigoside), twenty each. After treatment, the tibia of the mice in each group were subjected to sacral HE staining. The number of osteoclasts was counted, and the levels of oxidative related factors in serum were determined by enzyme-linked immunosorbent assay (ELISA). Results: The MTT results showed that compared with the blank control group [(100±3.7)%], the cell survival rate decreased to (44.1±5.7)% after treatment with dexamethasone, and the survival rate increased to (79.7±3.8)% after treatment with 5.0 μmol/L of curculigoside. The cell survival rate decreased to (59.1±4.7)% after H₂O₂ treatment, and the survival rate increased to (80.8±3.5)% after treatment with 2.5 μmol/L of curculigoside. The results of Western blotting showed that the expression of type Ⅰ collagen and integrin β1 in MG63 cells was significantly increased after 1.0, 2.5 and 5.0 μmol/L of curculigoside for 1, 7 and 14 days compared with 0 μmol/L of curculigo side for the same period. After increasing (P<0.05), the expression of Osterix and osteocalcin was significantly increased after 1 day of incubation (P<0.05). However, compared with 0 μmol/L curculigoside treatment, the expression of osteopontin in MG63 cells was not significantly different after incubation with 1.0, 2.5, 5.0 μmol/L of curculigoside for 7 and 14 days (P>0.05). Compared with the blank group, the number of tibia osteoclasts in the osteoporosis model group increased. In the low-dose and high-dose groups of curculigoside, the tibia cortex was more continuous and the number of osteoclasts decreased. Compared with the blank group, the activity of oxygen in the osteoporosis model group was significantly increased (P<0.05), and superoxide dimutase and catalase were significantly decreased (P<0.05). Conclusions Curculigoside promotes the differentiation of MG63 cells by increasing the expression of osteoblast differentiation-related proteins, and has a certain therapeutic effect on dexamethasone-induced osteoporosis mice.

Objective:To evaluate the effect of micro-implant assisted rapid palatal expansion (MARPE) in patients with different radiographic stages of midpalatal suture maturation.Methods:Twenty-eight patients [7 males and 21 females; age (15.5±5.5) years] with maxillary transverse deficiency were selected in the Department of Orthodontics, Hospital of Stomatology, Jilin University from February 2017 to October 2019. According to the fusion of the midpalatal suture, the patients were divided into two groups: 10 patients [3 males and 7 females; age (19.9±6.9) years] were in fusion group and 18 patients [4 males and 14 females; age (13.0±2.4) years] were in non-fusion group. Each patient had cone-beam CT (CBCT) images taken immediately after the placement of micro-implants (T1) and the completion of maxillary expansion (T2). The CBCT images were analyzed using the Dolphin Imaging software to evaluate the amount of midpalatal expansion and the percentages of bony expansion, etc. Statistical analysis was carried out to compare the two groups.Results:After MARPE treatment, the amount of sutural expansion in fusion group was (3.23±1.45) mm while that in non-fusion group was (4.97±1.47) mm ( P<0.05). There was a statistically significant difference in the percentages of bony expansion efficiency between the non-fusion group (71±20)% and the fusion group (46±18)% ( P<0.05). Conclusions:Bony expansion efficiency was affacted by the radiographic stages of midpalatal suture maturation.

Objective:To investigate the effect of tocilizumab (TCZ) on ventricular arrhythmias (VAs) after myocardial infarction (MI) in Sprague-Dawley rats and explore its potential mechanism.Methods:The random number table method was used to divide 32 adult male Sprague-Dawley rats into 4 groups: Sham group, TCZ group, MI group and MI+TCZ group, with 8 rats in each group. The MI model was established by ligation of the left anterior descending branch of the coronary artery in the MI and MI+TCZ groups, and only sutured without ligation in the Sham and TCZ groups. TCZ was injected into the left superior cervical ganglion (SCG) of rats in the TCZ and MI+TCZ groups after successful modeling or sham operation, and the same amount of normal saline was injected in the Sham and MI groups. 24 h after successful modeling, ECG of rats in each group was recorded, heart rate variability (HRV, including low frequency power (LF), high frequency power (HF), LF/HF ratio), QT interval, QTc interval were calculated, and left ventricular effective refractory period (ERP) and VA inducibility were measured. Myocardial infarct size and tissue changes were observed with triphenyl tetrazolium chloride staining and HE staining. Real-time PCR analysis was used to detect the messager RNA (mRNA) expression of interleukin-6 (IL-6) and signal transducer and activator of transcription (STAT) 3 in SCG and potassium voltage-gated channel subfamily D member 2 (Kcnd2) in myocardial infarction periphery. The expression of c-fos in SCG was detected by immunofluorescence staining.Results:Compared with Sham group and MI+TCZ group, rats in MI group had higher LF and LF/HF ratio, longer QT interval and QTc interval, more VAs induced, lower HF and shorter ERP ( P all<0.05). Triphenyl tetrazolium chloride staining and HE staining showed that rats in the Sham and TCZ groups had normal myocardial tissue structure, those in the MI group had severe myocardial injury, and those in the MI+TCZ group had less myocardial injury than those in the MI group. Real-ime PCR analysis showed that compared with Sham group and MI+TCZ group, mRNA expression levels of IL-6 and STAT3 in SCG of rats in MI group were higher, and mRNA expression level of myocardial Kcnd2 was lower ( P all<0.05). Immunofluorescence staining showed that the content of c-fos in SCG of rats in MI group was higher than that of Sham group and MI+TCZ group ( P all<0.05). Conclusions:TCZ may reduce neural activity of the SCG after MI by inhibiting the IL-6/STAT3 signaling pathway, thereby alleviating myocardial injury and inhibiting VAs.