| Objective:To establish and improve the stage 3 pressure injury(PI)model in rats according to the principle of ischemia-reperfusion injury,thus verifing the mechanism of reactive oxygen species in the stage 3 PI of rats.Meanwhile,to examine the expression of integrin ?v?3,and to prepare the RGD-targeted ultrasound contrast agent(CA),thus observing the effect in the stage 3 PI model of rats.Methods:In the first part of this study,twenty rats were divided into experimental group and control group randomly.The experimental group used double magnets to commpress externally with regular circulation to establish a stage 3 PI model,which means compressed for 2h,relaxed for 0.5h,continuously compressed at night,and kept the above circulation for 3 days.On the contrary,the control group did not do any treatment.Then the degree of injury was shown by HE staining;the expression of integrin ?v?3 was detected by immunohistochemistry;the expression of reactive oxygen species was detected by immunofluorescence,the average fluorescence intensity was analyzed by software;and the serum superoxide dismutase activity and malondialdehyde content was measured.Then compare whether the difference is statistically significant.In the second part,thirty rats were randomly divided into normal group,blank group and targeting group,with 10 rats in each group.The rats in blank group and the targeting group were prepared stage 3 PI model according to the above method.Then,the normal group and the targeted group were evaluated by RGD-targeted CA and the blank group was evaluated by blank CA.Thus to observe the difference of the contrast-enhanced intensity before and after ultrasonic cavitation among the three groups.Results:(1)After the model was formed,the whole levels of skin in the experimental group were wounded,with the wound edges rolled,the subcutaneous tissue observed,but no muscle exposed(2)Histopathology showed that the lesion reached the subcutaneous tissue and muscle,but no damage in the control group.(3)The SOD content of the experimental group was significantly lower than that of the control group(P<0.05),and the MDA content was significantly higher(P<0.01).(4)The average fluorescence intensity of the reactive oxygen species in the experimental group was distinctly higher than that of the control group(P< 0.01).(5)The expression of integrin ?v?3 was positive in the experimental group,with neonatal capillary endothelial cells,neutrophils and epithelial cells were dyed.;Oppositly,the expression of integrin ?v?3 was negative in the control group.(6)There was a statistically significant difference value of the enhancement intensity between the 3groups before and after ultrasound cavitation(P<0.01).The difference value of targeted group was significantly higher than that of normal group(p<0.01),at the same time,significantly higher than that of blank group(p<0.01),while there were no significantly meaning of the difference value between normal group and blank group(p=1.00).Conclusions:(1)The method used in this study can establish stage 3 pressure injury successfully.(2)Reactive oxygen species produced by ischemia-reperfusion injury was an important factor in the stage 3 PI of rats.(3)Integrin ?v?3 is positively expressed in rats with stage 3 PI,suggesting that integrin ?v?3 can be used as a target site for RGD-targeted ultrasound contrast agents..(4)RGD-targeted ultrasound CA has good targeting effect on stage 3 PI.therefore,it may be a new imaging method for the diagnosis and treatment of PI. |
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