Objective:To evaluate the role of ferroptosis in hypoxia-reoxygenation (H/R) injury in cardiomyocytes cultured in high-fat high-glucose (HFHG) medium.Methods:Cardiomyocytes H9c2 cells were commonly cultured and divided into 3 groups ( n=20 each) using a random number table method: control group (C group), HFHG-H/R group and Ferrostatin-1 (Fer-1) plus HFHG-H/R group (Fer-1+ HFHG+ H/R group). H9c2 cells were cultured in a HFHG medium for 12 h and then exposed to 1%O 2-5%CO 2-94%N 2 for 4 h, followed by 2 h reoxygenation in a cell incubator.Fer-1 at a final concentration of 10 μmol/L was added while the cells were cultured in the HFHG medium in group Fer-1+ HFHG+ H/R.At 2 h of reoxygenation, the cell viability was measured using CCK-8 assay, the activity of lactate dehydrogenase (LDH) in the supernatant was measured using 2, 4-dinitrophenylhydrazine color method, the activity of reactive oxygen species (ROS) was measured by fluorescent probe DCFH-DA flow cytometry, and the expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), nuclear receptor coactivator 4 (NCOA4), and glutathione peroxidase 4 (GPX4) was detected by Western blot. Results:Compared with group C, the cell viability was significantly decreased, the activities of LDH release and ROS were increased, and the expression of ACSL4 and NCOA4 was up-regulated ( P<0.05), and no significant change was found in the expression of GPX4 in group HFHG+ H/R ( P>0.05). Compared with group HFHG+ H/R, the cell activity was significantly increased, the activities of LDH and ROS were decreased, and the expression of ACSL4 and NCOA4 was down-regulated ( P<0.05), and no significant change was found in the expression of GPX4 in Fer-1+ HFHG+ H/R group ( P>0.05). Conclusions:Ferroptosis is involved in the process of H/R injury in cardiomyocytes cultured in HFHG medium.

Objective:To determine the mechanical properties of our self-designed novel cross-locking intramedullary nails and the impact of number of conical locking nails on the fixation through a finite element analysis and specimen experiments.Methods:Mimics 19.0 and SolidWorks 2014 were used to create transverse fracture models of the olecranon which were subjected to fixation with respectively K-wire tension band (KTB) and our self-designed novel cross-locking intramedullary nails (NIN). The strengths of KTB and NIN fixation were analyzed by Ansys. Fifteen human ulna specimens were used to construct a transverse fracture model of the olecranon; an Instron E10000 mechanical testing machine was used to determine mechanical properties in fixation respectively with KTB, one NIN (NIN-1) and 3 NINs (NIN-3).Results:In the finite element analysis, in simulation of the forearm flexed at 45° under a 100 N load, the deformation of the fracture surface of the olecranon in fixation with KTB, NIN-1 and NIN-3 was respectively 0.131 mm, 0.123 mm and 0.121 mm. In the specimen experiments, in simulation of the forearm flexed at 45°, the maximum failure loads for fixation with KTB, NIN-1 and NIN-3 were (313.38±27.68) N, (528.56±53.58) N and (871.04±94.95) N, respectively, showing significant differences among the 3 groups ( P<0.05). The maximum failure load for NIN-3 fixation was significantly greater than that for KTB or NIN-1 fixation, and the maximum failure load for NIN-1 fixation was significantly greater than that for KTB fixation ( P<0.05). Conclusions:Compared with KTB fixation, NIN fixation is more convenient in operation and has better mechanical properties. NIN-3 fixation has the best mechanical properties.

Objective To study the effect of interlocking intramedullary nail on fixing transverse olecranon fracture. Methods Nine pairs of fresh ulna specimens were collected and the transverse fracture model of olecranon was established. Kirschner wire tension band and interlocking intramedullary nail were used to repair the fracture. Cyclic dynamic tension loads with amplitude of 25 N, mean value of 45 N and frequency of 05 Hz were applied to the triceps tendon under simulated elbow flexion conditions of 30°, 45° and 60°, respectively. The fracture displacements of specimens within 300 cycles were recorded in three groups. ResultsAt 30° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.831±0.333) mm and (3.723±2.390) mm, respectively. At 45° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.167±0.374) mm and (2.455±0.609) mm, respectively. At 60° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.407±0.342) mm and (3.112±1.025) mm, respectively. The fracture displacement of interlocking intramedullary nail was smaller. Conclusions The mechanical properties of interlocking intramedullary nail are better than those of Kirschner wire tension band, and the interlocking intramedullary nail is more stable and firmer for fixing transverse olecranon fracture. Moreover, the interlocking intramedullary nail is installed with the operating tool, thus the operation is more accurate and faster, and the operation efficiency is greatly improved.