Effects of different helmet-mounted devices on pilot's neck injury under simulated ejection.

The helmet plays an important role in protection of pilot's head and enhances the pilot's capabilities and performance significantly with the use of mounted devices such as the Night Vision Goggle (NVG). However, the use of helmet-mounted devices might increase the risk of injury due to the increased helmet weight and change in the centre of gravity of head. In this study, four helmets with different combinations of mounted devices were modelled in a validated human head-neck multi-body model to analyse their effects on the pilot's neck injury during simulated ejection. The probability of neck injury was evaluated and predicted using the Nij neck injury criteria and human injury risk curves, considering the tolerance of injury for upper and lower cervical segment. It was demonstrated that the helmet-mounted devices would increase the compression force and bending moment on cervical spine, especially for the lower cervical segments with higher Nij. In the cases with Night Vision Goggle, Nij of the lower cervical segment reached 0.54, which exceeded the requirement in aviation filed. For the cases with Visor, excessive extension occurred, resulting in a high Nij. The simulation results of this study could provide a reference for helmet and mounted devices design and offer a proposal for the protection of pilots during ejection.

[Protective effects of soybean isoflavone on human umbilical vein endothelial cell injury induced by H2O2 and lipopolysaccharide].

OBJECTIVE: To investigate the protective effects and related mechanisms of soybean isoflavone (SI) on human umbilical vein endothelial cells (HUVECs) injury induced by H2O2 and lipopolysaccharide (LPS). METHODS: H2O2 and LPS were used to induce HUVECs injury in vitro. Nine experimental groups were examined: control group, H2O2 (2 mmol/L for 4 h), LPS (2 mmol/L for 4 h), H2O2+low dose SI (1 mg/ml), H2O2+moderate dose SI (2.5 mg/ml), H2O2+high dose SI (5 mg/ml), LPS+low dose SI (1 mg/ml), LPS+moderate dose SI (2.5 mg/ml), LPS+high dose SI (5 mg/ml). The survival ratio of HUVECs was detected with MTT assay. The cultured cells were loaded by Fura-2/AM and the change of [Ca²âº] in HUVECs was measured by fluorospectrophotometry. The contents of malondialdehyde (MDA), superoxide dismutase (SOD), reduced glutathione (GSH-Px) were measured by the commercial kits. The levels of tissue plasminogen activator IL-6 in the supematant were measured by enzyme linked immunosorbent assay (ELISA) kits. Apoptosis rate of the HUVECs was analyzed by flow cytometry. RESULTS: H2O2 and LPS significantly decreased HUVECs viability, increased the contents of MDA, IL-6 and decreased the contents of SOD and GSH-Px, and increased the apoptosis rate [(37.8 ± 1.8)% and (38.9 ± 1.1)%]. Co-treatment with SI could reduce MDA and IL-6 while increase SOD and GSH-Px and reduce apoptosis in a dose-dependent manner. CONCLUSION: The findings demonstrate that soybean isoflavone could attenuate H2O2 and LPS induced injury in human umbilical vein endothelial cells through protecting mitochondrial function, improving antioxygenic activity, and suppressing the mobilization of cytosolic calcium.