| Objective1.To establish a stable and high reproducibility rat model of deep partial-thickness scald burn infection for the study of repair mechanism and treatment of burn.2.On the basis of the establishment of animal models,To study the therapeutic effect of the new nanocrystalline silver-zinc dressing on deep partial-thickness scald burn infection.Method1.Establishment of animal model:Self-made scald instrument(Temperature 94℃)was used to reproduce burn injury on both sides of the back in 40 SD rats for different duration(4,6,8,10,12s),with 8 rats for each duration.24 hours after injury,observe the general situation of the wound,histopathological biopsy,record the wound healing time,filter out the best duration of the deep partial-thickness scald burn.Another 30 SD rats were randomly divided into 3 groups,10 rats in each group.All of rats were treated in accordance with method of preliminary experiment.30 min after injury,the wound was cool down and excision of eschar.0.3ml of liquid containing 1×10~7CFU/ml,1×10~8CFU/ml,1×10~9CFU/ml Pseudomonas aeruginosa was respectively inoculated to the wound on one side,while the wound on the other side were treated with the same volume of normal saline as control.24h after injury,observed inflammation by histopathological.The number of bacteria in the scab was measured at 1,2,4,7 and 14 days after inoculation,and the wound healing time was recorded.Data were processed with test.2.Study on the effect of new nanocrystalline silver-zinc dressing:108 male SD rats were randomly divided into three groups,36 rats in each group.Two deep partial-thickness scald wounds infected with Pseudomonas aeruginosa were established in the back of rats with consistent area and depth.Group A used nano-silver dressing,group B used nanocrystalline silver-zinc dressing,group C used ordinary sterile dressings when dressing change.The concentrations of interleukin-1(IL-1),transforming growth factor beta(TGF-β),interleukin-10(IL-10)and tumor necrosis factor alpha(TNF-α)in the tissues were detected by ELISA at 3,6,10 and 14days after injury.Immunohistochemistry staining was used to observe the expression of inflammatory cytokines in group B,and the wound healing time of each group was recorded.Using SPSS18.0 statistical software for statistical analysis.Results1.Burn 8s was identified as injury time resulting in deep partial-thickness injury according to histological observation.Inoculation of 1×10~8CFU/ml,1×10~9CFU/ml bacteria in the rat wounds had obvious inflammatory cell infiltration,the latter infiltration performance was more obvious.1×10~7CFU/ml bacterial group wound inflammation was not obvious.The subeschar bacteria count within post inoculation 14 day which wound inoculated 1×10~9CFU/ml bacterial was more than 1×10~5CFU/g,and showed a continuous upward trend.The healing time(21.4±2.4)d was significantly longer than that of the normal saline control group(18.4±1.7)d(t=2.72,P<0.05).2.At 3rd,6th,10th and 14days after injury,the levels of inflammatory factors IL-1and TNF-αin group B were lower than those in group A and C,and the trend decreased with time prolonged.The difference was statistically significant(P<0.05).The concentration of IL-10 and TGF-βin group B was higher than those in group A and C,and the trend increased with time prolonged.The difference was statistically significant(P<0.05).Immunohistochemical staining was showed that the expression of inflammatory factor TNF-αin group B decreased with the prolongation of treatment time,and the expression of IL-10 increased gradually.The wound healing time of group B rats was(16.5±1.2)d,shorter than the group A(18.38±1.69)d and the group C(20.63±2.56)d,the difference was statistically significant(P<0.05).Conclusion1.Temperature 94℃,scald time 8s,resection of the crust after the inoculation concentration of 1×10~9CFU/ml of Pseudomonas aeruginosa can establish burn depth consistent,high repeatability,good stability SD rats deep partial-thickness and infection model.2.The new nanocrystalline silver-zinc dressing has a better anti-infection and healing effect on Deep partial-thickness scald burn infection. |
