Damage to the DPPC Membrane Induced by Shock Waves: Molecular Dynamics Simulations.

Shock waves have shown a promising application in biomedical membranes. What needs to be noticed is that a shock wave will cause damage to human tissues when it is too strong. The damage to dipalmitoylphosphatidylcholine membranes induced by shock waves was studied by adopting all-atom molecular dynamics. It was found that as the impulse increased, the membrane became increasingly disordered and the folds became more severe with more water molecules in the hydrophobic area. The membrane impact process was divided into three stages, namely, the shock stage, recovery stage, and aftereffect stage. It was observed that the membrane damage was recoverable during the impact when the impulse was less than 127 mPa s, but no membrane damage recovery was observed when the impulse was greater than 153 mPa s. Furthermore, with the impulse increasing, the maximum strain of the membrane also increased, which was linear with the impulse. Moreover, when the impulse was 153 mPa s, the maximum strain of the membrane turned to 0.34. After the shock simulations, the recovery simulations continued for a few nanoseconds, and it was found that all of the membranes recovered.

[Application of bronchoscopic lung volume reduction using one-way flap device in sheep model of heterogeneous emphysema].

OBJECTIVE: To evaluate the effectiveness of bronchoscopic lung volume reduction (BLVR) using one way flap device in sheep model of heterogeneous emphysema. METHODS: Six 6-month sheep (weight: 20-30 kg) were treated with localized papain instillations to generate heterogeneous emphysema, subsequently underwent BLVR using one way-flap device at subsegment. Lung functional residual capacity (FRC) was analyzed before and 8 weeks after operation. Animals were euthanized at the 8-week time point. Lungs were removed en bloc and inflated with a super syringe to look for areas of gross collapse. Samples were collected from collapsed and non-collapsed areas, fixed in 10% buffered formalin, made paraffin section and stained with hematoxylin-eosin (HE) to observe morphologic change of bronchi. RESULTS: BLVR was well tolerated without complications, and it reduced lung volumes (change in residual volume 49.5%). There was no evidence of infection, abscess, or granuloma formation, or allergic reaction. Scar tissue, generated by BLVR, replaced hyperinflated lung,improved respiratory function safely and consistently. CONCLUSION: BLVR using one-way flap device is a minimally invasive procedure and the stimulus of the devices to walls of bronchi is slight, moreover, the technique may attain effectiveness of surgery. Therefore maybe it will be a perspective treatment of chronic obstructive pulmonary disease.