Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced endogenous caspase-3 expression. Surviving cells were protected by the downregulation of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate or premature apoptosis.

This paper studies the crashworthiness characteristics of a fuselage section and its improvement. A full-scale three-dimensional finite element model of the fuselage section is developed using a nonlinear finite element code, PAM-CRASH. The simulation is implemented to determine the structural deformation and impact response in terms of peak loads and acceleration peaks at the floor-level, deformation mode, energy absorption, and structural integrity, and then to assess the crashworthiness of the fuselage section. By partitioning the total energy dissipated, it is shown that the frames and the supports of the cargo floor play important roles in the process of energy dissipation. Based on the results, an effective approach to improve the crashworthiness of the fuselage section is presented. The paper also provides an in-depth analysis in the deformation mechanism of the fuselage section under a vertical crash, which will be helpful to effectively prevent the cabin floor from heavily damage and maintain the integrity of the fuselage section.