[Research progress in methylation modification in tooth root development].

Methylation modification is one of the most common epigenetic modification regulation in eukaryotes, including histone methylation, DNA methylation, RNA methylation, etc., which plays an important regulatory role in physiological processes and pathologic occurrence and development. Tooth root development is carried out by both epithelial and mesenchymal cells and involves a variety of cell-molecular interactions. In recent years, a large number of studies have found that methylation plays a key role in the regulation of tooth root development and expands the mechanism network of tooth root development. In this paper, we review the role and mechanism of methylation modification during root development.

[Mechanism of paeoniflorin inhibiting apoptosis of hippocampal neurons of rats induced by lead acetate].

Objective: To investigate the effect and underlying mechanism of paeoniflorin on hippocampal neuron apoptosis induced by lead acetate. Methods: In September 2020, primary hippocampal neuronal cells were isolated and cultured from fetal rats, and identified using cellular immunofluorescent. MTT assay was used to measure the cell viability to determine the concentration and time of lead acetate-induced hippocampal neuron apoptosis. MTT was also used to evaluate the effect of paeoniflorin concentration on the apoptosis of hippocampal neurons induced by lead acetate. According to the results, different concentrations of paeoniflorin were selected to intervene hippocampal neuron cells, after 24 h, lead acetate was added to the cells, meanwhile, blank and model groups were set up, the content of reactive oxygen species (ROS) , superoxide dismutase (SOD) , lactate dehydrogenase (LDH) , malondialdehyde (MDA) and Caspase-3 were measured. Extracellular signal regulated kinase (ERK) , phosphorylated ERK (p-ERK) , p38 mitogen -activated protein kinases (p38MAPK) , phosphorylated p38MAPK (p-p38MAPK) , c-Jun N-terminal kinase (JNK) and phosphorylated JNK (p-JNK) protein expression in hippocampal neuronal cells were determined by Western blotting. Results: The isolated and cultured hippocampal neurons were identified by immunofluorescence chemical staining and then treated with lead acetate, MTT results showed that lead acetate had the best toxicity effect when treated for 24 h at a concentration of 25 µmol/L. Paeoniflorin showed no cytotoxic effect on hippocampal neuronal cells when the concentrations below 80 µmol/L. Compared with the model group, the activity of hippocampal neuronal cells was significantly increased after treating with 20, 40 or 80 µmol/L paeoniflorin (P<0.05) . Compared with the blank group, the ROS activity, LDH release level, MDA content and caspase-3 content were significantly increased (P<0.01) , and the SOD activity was significantly decreased (P< 0.01) in the hippocampal neuronal cells of the model group. Compared with the model group, the ROS activity, LDH release level, MDA content and caspase-3 content were obviously decreased (P<0.05) , SOD activity was significantly increased (P <0.01) after hippocampal neuronal cells were treated with 40 or 80 µmol/L paeoniflorin. Relative to the model group, the ratio of p-ERK/ERK were significantly up-regulated (P<0.01) , while the ratios of p-p38MAPK/p38MAPK and p-JNK/JNK were significantly down-regulated after hippocampal neuronal cells were treated with 40 or 80 µmol/L paeoniflorin (P<0.05) . Conclusion: Paeoniflorin may down-regulate the expression of p-p38MAPK and p-JNK protein, up-regulate the expression of p-ERK protein, and inhibit the apoptosis of hippocampal neurons induced by lead acetate through the MAPK signaling pathway.

[The Function of CD40/CD40L Pathway in Silicosis Fibrosis].

Objective: To investigate the role of CD40/CD40L Pathway in the formation of silicosis fibrosis. Methods: Totally 64 inpatients were recruited and assigned to the silicosis group and the control group, 23 in each group. The alveolar lavage fluid was collected from all patients and isolated. The expression of CD40L protein was detected by Flow Cytometry. The level of IL-8、The IL-6、INF-γ and MCP-1 was detected by ELISA. Two groups of BALF were co-cultured with HFL-1 cells, the expression of Collagen I and α-SMA was detected by Immunohistochemistry. Results: Compared with the control group, CD40L was highly expressed on T lymphocyte cells in silicosis group (P<0.05) , and the contents of IL-8、The IL-6、INF-γand MCP-1 in Silicosis group were significantly higher than those in control group (P<0.05) . After co-culture of BALF and HFL-1 cells, the expression levels of Collagen I and α-SMA in Silicosis group were significantly higher than those in control group (P<0.05) . Conclusion: CD40-CD40L cross-linking system can promote the activation of T cells, release inflammatory factors, promote the synthesis of collagen I and α-SMA by fibroblasts, make the lung fibrous tissue proliferate, and lead to the formation of silicosis fibrosis.

[Experimental study on the expression of α-SMA and HMGB1 in silicotic fibrosismodel rats interfered by lumbricus].

Objective: To observe the expression of alpha smooth muscle actin (α-SMA) and high mo-bility group protein B1 (HMGB1) in silicosis model rats interfered by lumbricus. Methods: 45 rats were ran-domly divided into the control group, model group and group interfered by lumbricus. The silicosis model rats were established. The group interfered by lumbricus were intragastric administered with lumbricus decoction by the 4 ml/kg dose. The control group and model group were ig administered with the equal amount of normal saline. Each group were killed 5 rats on the 7(th), 14(th) and 28(th) day. The lung tissues were stained with HE and Sirius red methods. The mRNA expressions of α-SMA and HMGB1 were determined with RT-PCR; The pro-tein levels of α-SMA and HMGB1 were determined with Western blotting. Results: Compared with the control group, the expression levels of α-SMA and HMGB1mRNA and protein in lung tissue of model group were grad-ually increased in the 7(th), 14(th) and 28(th) days, the difference was statistically significant (P< 0.01) . Compared with model group, the levels of α-SMA and HMGB1mRNA and protein in lung tissue of group interfered by lumbricus were gradually lowered in the 7th, 14th and 28th days, the difference was statistically significant (P<0.05, P<0.01) . Conclusion: Lumbricus inhibits the collagen deposition and the formation of silicosis pulmo-nary fibrosis, which may be related to the inhibition of HMGB1 expression and activation of α-SMA in lung tis-sue.

[Effect of blastocyst quality on the strategy of single blastocyst transfer in frozen-thawed cycles].

OBJECTIVE: To investigate the effect of blastocyst quality on the strategy of single blastocyst transfer in frozen-thawed cycles. METHODS: A retrospective analysis was performed in Reproductive Medicine Center, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region on clinical data of single frozen-thawed blastocyst transfer cycles from January 2008 to December 2013. All cycles were divided into four groups (AA, AB/BA, BB, BC/CB) according to the blastocyst score, then the clinical outcomes were compared between groups. And on this basis, the clinical outcomes were further explored when the group of outcomes with single blastocyst transfer wasn't ideal, which would diverted to transfer two blastocyst. RESULTS: In single frozen blastocyst transfer cycles, the clinical pregnancy rate of each group with the blastocyst scored AA, AB/BA, BB, BC/CB were 61.4% (470/765), 51.2% (330/645), 40.5% (407/1 005), 22.9% (60/262), live births rate in each group were 52.2% (399/765), 41.2% (266/645), 30.4% (306/1 005), 13.7% (36/262), and the abortion rate were 13.6% (64/470), 16.7% (55/330), 21.4% (87/407), 35.0%(21/60), separately. This showed that the clinical pregnancy rate and live births rate decreased significantly with the decline of blastocyst quality (P<0.01), but the abortion rate showed significant upward trend (P<0.01). When single blastocyst scored ≥BB grade transferred, an acceptable clinical pregnancy rate (>40%) and live births rate (>30%) could be obtained, however, the clinical pregnancy rate of 22.9% and live births rate of 13.7% could only be acquired when blastocyst scored BC/CB only transferred one embryo, which significant lower than those of each group scored ≥BB grade (P<0.01). So, after that, the blastocyst scored BC/CB were further divided into two groups (single blastocyst transferred versus two blastocyst transferred) to investigate, then the result showed that the clinical pregnancy rate [22.9% versus 38.5%(67/174),P<0.01] and live births rate [13.7% versus 30.5%(16/67),P<0.01] were significantly increased in the group of two blastocyst transferred compared with the group of one blastocyst transferred, and the abortion rate was also significantly decreased from 35.0% to 17.9% (12/67;P<0.05). So when two blastocyst scored BC/CB were transferred, the clinical outcomes were similar to the group of one blastocyst scored BB transferred (P>0.05). CONCLUSIONS: Of single blastocyst transfer in frozen-thawed cycles, the clinical pregnancy rate and liver births rate showed significant upward trend, but the abortion rate showed significant downward trend, with the decline of blastocyst quality. When the blastocyst scored ≥BB grade, the single blastocyst transfer could be considered to be performed.