AIM:To investigate the effect of hydrogen sulfide(H2S)on ferroptosis and functional impairment induced by oxidized high-density lipoprotein(ox-HDL)in human umbilical vein endothelial cells(HUVECs),and to ex-plore its mechanisms.METHODS:The HUVECs were cultured in vitro and exposed to 200 mg/L ox-HDL,ferroptosis in-hibitor ferrostatin-1(Fer-1),protein kinase B(PKB/Akt)inhibitor MK-2206 2HCl(MK),Akt agonist SC79,and/or H2S for 24 h.Western blot was used to identify the relevant proteins.Intracellular levels of reactive oxygen species(ROS)were analyzed by flow cytometry and immunofluorescence staining.Intracellular iron was measured using an iron detection kit.The number of monocytes adhering to endothelial cells was counted using the monocyte adhesion assay.RESULTS:Compared with control group,acyl-CoA synthetase long-chain family member 4(ACSL4)protein expression in ox-HDL group was elevated by 1.45-fold(P<0.01),glutathione peroxidase 4(GPX4)protein expression was decreased by 29.79%(P<0.05),and ROS levels and iron ion content were elevated by 4.81-fold and 1.40-fold,respectively(P<0.01).The ratios of p-PI3K/PI3K and p-Akt/Akt were decreased by 45.65%and 41.68%,respectively(P<0.01),endo-thelial cell function-related protein IL-6,ICAM-1 and TNF-α expression was elevated 1.18-fold,1.24-fold and 1.41-fold(P<0.05),respectively,eNOS protein expression was decreased by 35.24%(P<0.01),and monocyte adhesion was ele-vated 3.43-fold(P<0.01).Compared with ox-HDL group,the endothelial cell iron death-related protein ACSL4 was de-creased by 22.32%(P<0.05),GPX4 was increased by 1.27-fold(P<0.01),and the p-Akt/Akt ratio was increased by 1.52-fold(P<0.01)in ox-HDL+H2S group.The fluorescence microscopy results showed that the ROS was decreased by 50.35%(P<0.01).The IL-6,ICAM-1 and TNF-α protein expression was decreased by 13.34%,9.83%and 13.46%(P<0.05),respectively,eNOS was elevated by 1.22-fold(P<0.01),and the number of monocyte adhesion was de-creased by 59.05%(P<0.01).Compared with ox-HDL group,GPX4 protein expression in ox-HDL+SC79 group was ele-vated by 1.49-fold(P<0.01),ACSL4 expression was decreased by 20.72%(P<0.05),and ROS and iron ions were de-creased by 59.31%and 23.85%(P<0.05),respectively.Compared with ox-HDL+H2S group,GPX4 protein expression was decreased by 21.28%,and ACSL4 protein expression was increased by 1.16-fold in ox-HDL+H2S+MK group(P<0.05).CONCLUSION:H2S activates Akt to inhibit ox-HDL-induced ferroptosis in HUVECs and alleviate their func-tional damage.

Objective:To develop a specialized clival-cervical plate fixation (CCPF) for anterior surgery to treat craniovertebral instability, and to compare it with a posterior occipitocervical fixation (POCF) in biomechanical validation.Methods:Based on the measurement of 40 adult dry bones and 30 volunteers CT images, the clival-cervical plate was designed and manufactured. 8 cadaveric specimens (occiput-C 3) were tested in five conditions including the intact status, the intact+CCPF status, the injury status, the injury+CCPF status, and the injury+POCF status. Specimens were applied a pure moment of 1.5 N·m in flexion, extension, lateral bending, and axial rotation. Calculating and comparing the range of motion (ROM) and neutral zone (NZ) for the occiput to C 2. The effects of different fixation methods on the distribution of ROMs at the occipitocervical region were compared. Results:The injury+CCPF status constrained ROMs to 1.7° in flexion ( q=4.68, P=0.055) , 1.2° in extension ( q=0.39, P=0.9922) , 2.8° in lateral bending ( q=1.25, P=0.814) , and 4.3° in axial rotation ( q=5.08, P=0.035) , resulted in larger ROM in axial rotation but similar ROMs in other directions ( P>0.05) when compared with the injury+POCF status. There were no significant differences between the above two fixation methods in flexion-extension ( q=1.94, P=0.554) , lateral bending ( q=1.79, P=0.611) and axial rotation ( q=2.14, P=0.478) for the NZs. For the flexion, extension,lateral bendingand axial rotation direction, the proportion of the C 1, 2 ROM to the overall ROM was 28%, 25%, 34% and 56% respectively in the injury+CCPF status, and it was 59%, 53%, 42% and 71% respectively in the injury+POCF status. Conclusion:CCPF is a biomechanically effective alternative or supplemental method of POCF for the craniocervical instability.