| Dressings which are applied to daily life and clinical have only a simple function of hemostasis at present; In recent years, the biological dressings, functions are only to clean superficial wounds and to promote wound healing, which can not dealt with traumatic wounds, particularly naval battle wounds. We create a novel dressing which is made from chitosan, alginate and polyvinyl alcohol (PVA),which has the advantages of hemostasis, inflammation, promote healing, waterproof and no need to replace at short-term. Which could reduce the rate of disability and death of the wounded who fell into the sea .we would prove whether the dressing has the above-mentioned functions and provide the basis for clinical applications through animal experimentation.Part oneObjective To study the hemostatic properties of a novel dressing,which is made from chitosan and alginate (developed by our project team,have applicated national patent).Methods Bleeding time were measured for bilateral back incisions(5 incisions on each side)in 4 New Zealand white rabbits. Using a randomized,blinded experimental design, one incision in each animal was treated with chitosan/alginate dressings, the other was treated with gelatin sponge. After bleeding stopped, put the chitosan/alginate dressings and gelatin sponge into cyanmethemoglobin agent and carefully cleaned, absorbance was detected by spectrophotometer at 540 nm wavelength, which behalf of the amount of bleeding.Results The group of chitosan/alginate dressings adhered to incision better than the gelatin sponge group. the bleeding time of chitosan/alginate dressings group and gelatin sponge group were 87.7±19.1 seconds and 170.7±22.6 seconds, respectively. Hb absorbance value were 1.131±0.44 and 1.733±0.733, respectively, the two groups of data have significant difference by statistical analysis (P<0.01), Chitosan/alginate dressings group is significantly better than gelatin sponge group.Conclusion Chitosan/alginate dressings hemostasis performance is better. Part twoObjective To observe the Chitosan / alginate dressings' effect on wound immersed in seawater.Methods To establish the model of rat's skin wounds, Taking the healthy SD rats 25 and weighing 250～300 g, a 1.8cm skin round incisions were made bilaterally along the SD rats' spine. The left side is experimental group, the right side is control. Then the wounds were immersed in the manmade seawater for 1h.In the experimental group, wounds were treated with chitosan/alginate dressings, whereas the Sterile gauze was used in the control group. To observe the whole condition and record the days of healing. The 2.0 cm×2.0 cm skin tissues including the wounds were removed 3,5,7,10,12 days after the operation, stained with HE and Immunohistochemistry. To observe the histological changes and the expression of Epidermal Growth Factor(EGF) and basic Fibroblast Growth Factor(bFGF) by Ordinary microscope.Results In the experimental group, wound inflammatory response was lighter and crust shrinked faster. 2,The wounds healing time is 11.68±0.57 d in experimental group versus 12.51±0.54 d in control, there is a significantly difference between them (P<0.05). Granulation tissue proliferation and cell infiltration, Collagen tissue proliferation, wound shrinkage and epithelization were observed to occur after the operation for 3 days in the experimental group.10 days after the operation, Collagen tissue lined regularly, epithelization basically completed and appendages of the skin were also observed.12 days after the operation, The wound has healed. Reversely, at the same time point,cell infiltration and epithelization were observed later, and granulation tissue with ulcers was observed. Immunohistochemical results, EGF and bFGF were expressed in each time point, especially in the 3rd and 5th days in the experimental group. there was less expressed in the Seventh, tenth and twelfth days. And there was nothing or less in the control at the same time point.Conclusion Chitosan/alginate dressings have the healing effect on wound immersed Seawater, but the mechanism remains to be further in-depth study.
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