Objective:To investigate the effects of miRNA-499a-5p targeting CD38 on cardiomyocyte injury induced by hydrogen peroxide (H 2O 2) and the possible mechanism. Methods:H9c2 cardiomyocytes were cultured in vitro and induced with H 2O 2 to establish the cardiomyocyte injury model. Four groups including control, H 2O 2, H 2O 2+ negative control (NC) and H 2O 2+ miRNA-499a-5p groups were set up. Real-time quantitative PCR (RT-qPCR) and Western blot were used to detect the expression of miRNA-499a-5p and CD38 in cardiomyocytes, respectively. MTT assay was used to measure the survival rates of cardiomyocytes. The levels of reactive oxygen species (ROS) and the activity of lactate dehydrogenase (LDH) were analyzed with test kits. Annexin V-FITC/PI double staining method was used to detect the apoptosis rates of cardiomyocytes. Western blot was used to detect the expression of B-cell lymphoma/leukemia-2 (Bcl-2), Bcl-2-related X protein (Bax), phosphoinositide 3-kinase (PI3K), phosphorylated PI3K (p-PI3K), protein kinase B (Akt) and phosphorylated Akt (p-Akt). Dual luciferase reporter assay was used to detect the targeting relationship between miRNA-499a-5p and CD38. Results:Compared with the control group, the expression of miRNA-499a-5p, Bcl-2, p-PI3K and p-Akt and the survival rate of cardiomyocytes were significantly reduced in the H 2O 2 group ( P<0.05), while the expression of CD38 and Bax, ROS level, LDH activity and the apoptosis rate were significantly increased ( P<0.05). Compared with the H 2O 2 group, the expression of miRNA-499a-5p, Bcl-2, p-PI3K and p-Akt and the survival rate of cardiomyocytes were significantly increased in the H 2O 2+ miRNA-499a-5p group ( P<0.05), while the expression of CD38 and Bax, ROS level, LDH activity and the apoptosis rate were significantly decreased ( P<0.05). Dual luciferase reporter assay confirmed that CD38 was a target gene of miRNA-499a-5p. Conclusions:miRNA-499a-5p could alleviate H 2O 2-induced cardiomyocyte injury by inhibiting the expression of CD38 and the PI3K/Akt signaling pathway might be involved.

Objective: To investigate the effects of miR-27b targeting ten-eleven translocation methylcytosine dioxygenase 2 (TET2) on oxidized low-density lipoprotein (ox-LDL) induced inflammatory responses and apoptosis in endothelial cells. Methods: Double luciferase reporter gene analysis verified the targeting effect of miR-27b on TET2. Human umbilical vein endothelial cells (HUVECs) were induced by ox-LDL in vitro. Eight groups were set up including control group, ox-LDL group, ox-LDL+ anti-miR-con group, ox-LDL+ anti-miR-27b group, ox-LDL+ pcDNA group, ox-LDL+ pcDNA-TET2 group, anti-miR-27b+ si-con group and anti-miR-27b+ si-TET2 group. qRT-PCR was used to detect the expression of miR-27b and TET2 at mRNA level. Cell viability was detected by MTT assay. Cell apoptosis rate was detected by flow cytometry. Western blot was used to detect the expression of TET2, Cyclin D1 and caspase-3 at protein level. Results: TET2 was the target gene of miR-27b. TET2 expression could be negatively regulated by miR-27b. ox-LDL increased the expression of miR-27b and reduced the expression of TET2 in HUVECs. The secretion of inflammatory factors and apoptosis rates of HUVECs in the control, ox-LDL+ anti-miR-27b, ox-LDL+ pcDNA-TET2 and anti-miR-27b+ si-con groups were significantly lower than those in the ox-LDL, ox-LDL+ anti-miR-con, ox-LDL+ pcDNA and anti-miR-27b+ si-TET2 groups, respectively (P<0.05). Conclusions miR-27b promoted ox-LDL-induced inflammatory responses and apoptosis in endothelial cells through down-regulating the expression of TET2.

OBJECTIVE: To explore the effect of wearing earphone to listen to music on the high-frequency noise-induced hearing loss(NIHL) in noise-exposure workers. METHODS: A total of 651 male noise-exposure workers in an automobile manufacturer were selected as study subjects by using judgment sampling method. The level of noise exposure in the individuals and the pure tone hearing threshold were tested. According to the frequency of wearing earphone to listen to music after work, the subjects were divided into low-, medium-and high-frequency earphone-using groups, with 60, 436 and 155 workers in each group, respectively. The effects of wearing earphone to listen to music combined with occupational noise exposure on high-frequency NIHL were analyzed. RESULTS: The high-frequency NIHL detection rate of the study subjects was 31.3%(204/651). The detection rate of high-frequency NIHL in these three groups from low to high was low-, medium-and high-frequency earphone-using groups(P<0.01). The detection rate of high-frequency NIHL in the high-frequency earphone-using group was higher than that of the low-and medium-frequency earphone-using groups(43.2% vs 25.0%, 43.2% vs 28.0%, P<0.01). Multivariate logistic regression analysis showed that wearing earphones to listen to music was a risk factor for high-frequency NIHL in noise-exposure workers(P<0.01) after eliminating the influence of confounding factors such as age, length and level of noise-exposure, and wearing anti-noise ear plugs. The higher frequency of wearing earphone to listen to music, the higher risk of high-frequency NIHL. CONCLUSION: Wearing earphone to listen to music after work and occupational noise exposure had a synergistic effect on high-frequency NIHL in noise-exposure workers.