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@#Objective To investigate the protective and cure effects of dexamethasone on bleomycin-induced pulmonary fibrosis.Methods32 rats were randomly divided into the control group (C-group, n=8), injury group (I-group, n=12) and dexamethasone group (D-group, n=12). The acute pulmonary model was established by intratracheal injection of bleomycin with rats of the I-group and D-group; while rats of the C-group injected with distilled water. After that, rats of the D-group were injected with dexamethasone sodium phosphate in intraperitoneal every day, those of the C-group and I-group were injected with saline. The animals were killed on the 3rd, 7th, 14th, and 27th days after treatment, and tests of bronchoalveolar lavage fluid (BALF), total lung collagen content and lung tissue processing were performed.ResultsPathological evidence of the I-group rats demonstrated that the alveolar compartment companied with massive inflammatory cell invasion and a number of myofibroblast proliferation became more thick. However, lung injury in the D-group rats got better than that in the I-group. Neutrophil percentage achieved peak in both I-group and D-group on the 7th day. But the neutrophil ratio in the D-group was significantly lower than that of the I-group on the 7th day ( P<0.05) and the 14th day ( P<0.01). Total lung collagen content achieved peak on the 14th day both in I-group and D-group, but that of the I-group was significantly higher than that of the C-group ( P<0.01) and the D-group was significantly lower than the I-group ( P<0.01).ConclusionDexamethasone plays a protective and cure role in lung fibrosis by efficiently inhibiting the gather and invasion of neutropils and restraining the increase of collagen secreted by proliferous fibroblasts.
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A porcine heart valve was irradiated by Ultraviolet (UV) rays (10 W, 254 nm) for 2, 4, 8 and 24 hours at 4 degrees C to cross-link the structural collagen matrix. The degree of cross-linking was evaluated by assaying the released amount of hydroxyproline (Hyp) from the matrix, and comparing it with the positive controls of valves treated by glutaraldehyde (GA) solution (0.625 wt%) and the negative controls of non-treated fresh valves. The undigested weight ratio of the specimens increased by increasing the UV irradiation time. The undigested weight of the leaflets, tunica interna and tunica externa of the fresh, GA-treated and UV-irradiated specimens after collagenase digestion was compared. As UV irradiation increased, the amount of released hydroxyproline was gradually decreased until 8 hours of irradiation, after which the released hydroxyproline-reduction occurred slightly until 24 hours of irradiation time in this system. A total 47.68% of the hydroxyproline in the valve was cross-linked by UV irradiation after 24 hours, while 73.74% of the hydroxyproline in the positive control was crossed-linked. Light microscopic observation revealed that the typical crimp pattern of collagen fibers decreased and was rearranged into a dense flattened pattern as the UV irradiation induced interfibrilar cross-linking. GA-treated valves demonstrated a denser matrix pattern than the UV-irradiated specimens. Cross-linked collagenous tissue prepared by UV irradiation would be useful for improving durability and reducing the disadvantages related to using a chemical cross-linking agent.