[Protective effects of dexamethasone combined with valsartan on chronic obstructive pulmonary disease in mice and its mechanism].

Objective: To investigate the possible protective effects of combined dexamethasone and valsartan against cigarette induced chronic obstructive pulmonary disease (COPD) in mice. Methods: Forty C57BL/6 mice were randomly divided into control group, COPD group, dexamethasone treated group, valsartan treated group and dexamethasone + valsartan combined treatment group, with 8 mice in each group. Mice in COPD group were exposed to cigarette for 8 weeks. On the basis of cigarette exposure, mice in dexamethasone treated group were intraperitoneally injected with dexamethasone (2 mg / kg) before cigarette exposure for 5-8 weeks. Mice in valsartan treated group were intraperitoneally injected with valsartan (30 mg/kg) before cigarette exposure for 1-8 weeks. Dexamethasone (2 mg/kg) and valsartan (30 mg/kg) were injected intraperitoneally into mice in the dexamethasone + valsartan combined treatment group. After 8 weeks, the lung tissues and bronchoalveolar lavage fluid (BALF) of mice in each group were collected. The pathological score of lung tissue was evaluated. The activities of superoxide dismutase(SOD) and matrix metalloproteinase-9 (MMP-9), and the contents of malondialdehyde (MDA), intracellular adhesion molecule-1 (ICAM-1), C-reactive protein (CRP) and nitric oxide (NO) in BALF were determined. Results: Compared with the control group, COPD mice had emphysema and alveolar congestion, the levels of MDA, ICAM-1, MMP-9, CRP and lymphocytes in BALF were increased, while the levels of SOD, macrophages and NO were decreased (all P＜0.05). Compared with COPD group, there was no significant improvement in emphysema and alveolar congestion, the levels of SOD and NO in BALF were increased, and the levels of MDA, lymphocytes and macrophages were decreased in dexamethasone or valsartan group (all P＜0.05). Compared with dexamethasone or valsartan group, the dexamethasone + valsartan combined treatment was more effective in preventing pulmonary emphysema and alveolar congestion caused by cigarette smoke. The levels of MDA, ICAM-1, MMP-9, CRP and lymphocyte in BALF were decreased, while the levels of SOD, macrophage and NO were increased (all P＜0.05). Conclusion: Compared with dexamethasone or valsartan, dexamethasone combined with valsartan has a more effective protective effect in COPD mice by inhibiting oxidative stress and inflammation.

Evaluation of non-local means based denoising filters for diffusion kurtosis imaging using a new phantom.

Image denoising has a profound impact on the precision of estimated parameters in diffusion kurtosis imaging (DKI). This work first proposes an approach to constructing a DKI phantom that can be used to evaluate the performance of denoising algorithms in regard to their abilities of improving the reliability of DKI parameter estimation. The phantom was constructed from a real DKI dataset of a human brain, and the pipeline used to construct the phantom consists of diffusion-weighted (DW) image filtering, diffusion and kurtosis tensor regularization, and DW image reconstruction. The phantom preserves the image structure while minimizing image noise, and thus can be used as ground truth in the evaluation. Second, we used the phantom to evaluate three representative algorithms of non-local means (NLM). Results showed that one scheme of vector-based NLM, which uses DWI data with redundant information acquired at different b-values, produced the most reliable estimation of DKI parameters in terms of Mean Square Error (MSE), Bias and standard deviation (Std). The result of the comparison based on the phantom was consistent with those based on real datasets.