| ObjectiveWith the development of modern society needs,marine business activities have become increasingly frequent,people who operate or battle on the sea are easy to be wounded by all kinds of injuries.Technically,the wound is often contaminated by seawater or even directly immersed in sea water,which would probably do more harm to the whole body and affect wound healing process.There are more and more scholars at home and abroad pay attention to the effects of seawater immersed burn injury,but so far the sea water immersion on shallow ? degree burn injury's effects and treatment measures are scarcely reported,clinical treatment is scarcer.The study based on a model of 5%TBSA rats with shallow ? degree burned as model,to investigate the effect of seawater immersion on shallow ? degrees injury and its mechanism.From the certain aspects of pathological change in wound,wound tissue and serum TNF-?,SOD,MDA content changes,to provide theoretical reference for clinical treatment of the burn with seawater immersion,also explore the feasibility of topical treatment.Methods1.Animal model:70 SPF level Wistar rats weighted 180?220g were randomly divided into four groups:normal control group(7 rats),scalded group(21 rats),the scalded group immersed into fresh water(21 rats),the scalded group immersed into sea water(21 rats).Then the latter three groups were further grouped according to the immersing time,2 hours after immersion,4 hours after immersion,6 hours after immersion,and there are 7 rats in each group.2.Injury method:0.3%pentobarbital sodium(1ml/100mg)was injected into the abdominal cavity of rats for anesthesia,then their backs'hair were shaved by the electric machine.Except group A,hands and feet of the other rats were tied up and put the hair removal area under constant temperature water bath at 70?in 12s,causing 5%TBSA ?° scald(already proved by patholpgy),then put group C and group D rats,body below upper limbs in fresh water and sea water,immesing time were 2 hours,4 hours,6 hours.3.Test index and Methods:Wound were observed by eyes at 2 hours,4 hours,6 hours after scalded.Histopathological changes were observed by light microscopy at 2 hours,4 hours,6 hours after scalded.Then we collect the venous blood to be tested.After hepar treatment,serum samples were extracted immediately.Then we cut wound skin tissues,after tissues homogenate,supernatants were extracted.TNF-?content was determined by ELSA method,the MAD content was determined by TBA method,the SOD content was determined by hydroxylamine method.4.Data processing:All the data were showed in the form mean±SD,.and analyzed by statistical software of SPSS19.0.All the data were analyzed by factorial analysis of variance?One-way ANOVA,method of multiple comparisons between Group using Tamhane?Welch?Brown-Forsythe(B)test and LSD,P<0.05 as significance difference.Results1?Pathological and morphologic changes:In normal control group(group A),the surface epithelial cells were arranged orderly and continuously and epithelial cells were well stained under light microscopy.The dermis tissue and accessory structure was clear and complete,dermal collagen was well arranged under light microscopy.In scalded group(group B),the epidermal layer was clear,but the cells were swollen,the structure was clear but the nucleus structure was blurred.There was blister formation in the epidermis and edema in dermal cell.Interstitial was loose,vascular was dilatation and congestion,which is the performance of shallow ? degree.In fresh water group and sea water group,the epithelial layer of wound's was massive decreasing,some of the epidermal cells were disrupting,the structure of nucleus was unclear,and the edema in dermal cell was more serious than before,moreover,there were inflammatory cells in dermis layer too,and this was more obvious in sea water group.2.The morphological changes of the wound under electron microscope:In normal group,the cuticle is arranged orderly and continuously,the integrity basement membrane of dermal capillary can be seen,the villi and the edge of endothelial cells is clear,the connection between endothelial cells and the structure of cell can be seen clearly.In scalded group,the cuticle arranged is in a mess,the edge of cell is unclear,karyopyknosis and some organelles vanishing,the integrity basement membrane of dermal capillary can be seen,and the lumen was saturated with large number of erythrocytes.Endothelial cell swelling,the intercellular spaces dilatation and cytoplasm rarefaction.In fresh water group,the cuticle is arranged beter than scalded group,the integrity basement membrane of dermal capillary can be seen,the endothelial cell was swelling and we can see many erythrocytes in the lumen.In sea water group,the cuticle is disorganized and the integrity basement membrane of dermal capillary is disappeared,some erythrocytes were found outside the vessels,endothelial cell swelling and with the cytoplasm rarefaction.Cytoplasm were filled with vacuoles and endothelial cell lose their structural integrity,some cells shrivel and some cells have came off,resulted in the formation of hollow.3.Change of the supernatant of wound tissue homogenate's TNF-?.SOD?MDA content:Compared with the healthy control group[(247±27)pg/ml],the serum TNF-a levels of simple scald group increased after scalded in 2 and 4h[(675±122,367±54)pg/ml](P<0.05?P<0.01),but decreased obviously after scaled in 6h[(147±27)pg/ml](P<0.01);the serum TNF-a levels of fresh water group made no difference after scalded in 2 and 4h(P>0.05),but decrease obviously after scaled in 6h[(90±24)pg/ml](P<0.01);the serum TNF-? levels of sea water group all obviously increased after scalded in 2,4 and 6h,the content were[(1646±5 8,2086± 114,2 951±58)pg/ml]respectively(P<0.01).Compared with the healthy control group[(364±123)U/ml],the serum SOD levels of simple scald group increased after scalded in 2 and 4h[(489±13,447±14)U/ml](P<0.05),but made no difference after scalded in 6h(P>0.05);the serum SOD levels of fresh water group made no difference after scalded in 2 and 4h(P>0.05)s but was lower than healthy control group after scalded in 6h[(282±13)U/ml](P<0.05);the serum SOD level of sea water group was higher than healthy control group after scalded in 2h[(461±23)U/ml](P<0.05),but were lower than healthy control group after scalded in 4 and 6h[(226±8,205±10)U/ml](P<0.01).Compared with the healthy control group[(5.4±1.5)nmol/mL],the serum MDA levels of simple scald group,fresh water group and sea water group all obviously increased after scalded in 2,4 and 6h[(14.2±1.2,18.2±1.1,39.1±2.7)(18.8±1.2,29.9±1.1,52.613.9)(19.1±1.5,35±3.3,55.4±9.8)nmol/mL](P<0.01).4.Change of serum TNF-??SOD?MDA content:Compared with the healthy control group[(63±25)pg/ml],the serum TNF-a levels from wound tissues of simple scald group and sea water group all increased after scalded in 2,4 and 6h[(496±89,263±39,108±19)(1373±15,1742±12,2136144)pg/mg](P<0.05 or P<0.01);the serum TNF-a level from wound tissues of the fresh water group obviously increased after scalded in 2h[(276±46)pg/mg](P<0.01),but made no difference after scalded in 4 and 6h(P>0.05).Compared with the healthy control group[(46±6)U/mg],the serum SOD levels from wound tissues of simple scald group and fresh water group all increased after scalded in 2,4 and 6h[(304±27,259±31,152±14)(258±22,215±15,78±19)U/mg](P<0.05 or P<0.01);the serum SOD levels from wound tissues of sea water group increased after scalded in 2 and 4h[(279±28,176±10)U/mg2(P<0.01),but made no difference after scalded in 6h(P>0.05).Compared with the healthy control group[(6.3±0.8)nmol/mg],the serum MDA levels from wound tissues of simple scald group,fresh water group and sea water group all increased after scalded in 2,4 and 6h[(10.9±1.2,14.1±1.5,31.4±2.4)(15.1±1.6,23.9±1.7,41.7±5.4)(19.5±2.3,28.2±3.2,48.±6.9)nmol/mg](P<0.01)Conclusion1.After scalding in rats,seawater immersion can aggravate the inflammatory reaction of the whole body and the local wound,and thus deepen the wound injury.The possible mechanism may be seawater hypertonic,alkaline state led directly to the body tissue dehydration,degeneration and necrosis.Moreover,the low temperature and strong heat dissipation can lead to sharp decline in body temperature caused by the disturbance of hemodynamics.Thus enhance the wound and make more ecological organizations into the necrotic tissue.And the more necrotic tissue,the more inflammatory factors,which will further aggravate systemic tissue injury and wound.2.After scalding in rats,the oxygen free radical injury was aggravated by the immersion of seawater.The mechanism may be that the characteristics of low temperature and strong heat dissipation of seawater directly lead to microcirculation disturbance,increase the energy metabolism disorder,increase the generation of oxygen free radicals,and enhance the lipid peroxidation reaction.3.With seawater immersion in rats after scalding,inflammatory reaction and oxygen free radical injury severity and immersion time was significantly correlated with immersion time.The longer time of immersion the greater extent of damage,which indicating that seawater immersion has a negative effect on the body injury. |
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