Study On The Mechanisms Of Acute Lung Injury On Scalded Rats Combined Seawater Immersion

ObjectiveWith the development of modern society and marine business activities have become increasingly frequent,and with the surrounding ocean situation is more complex,and the war at sea maritime accidents with increasing incidence of burn wounds in[1]it is likely to suffer from water pollution,facing two hit by seawater immersion.The water has high permeability,low temperature,alkaline,with special physical and chemical properties of bacteria,previous studies have shown that burn injury with seawater immersion will cause the body electrolyte and acid-base imbalance,hypertonic dehydration,hemodynamic turbulence and severe infection,causing multiple organ failure in[2].Severe burn often involves multiple system injuries,including acute lung injury is one of the serious complications of high mortality.Acute respiratory distress syndrome(ARDS)caused by acute respiratory distress syndrome[4]is an important cause of death in the early stage of severe burn.Acute lung injury(ALI)is the early stage of acute ARDS,while ARDS is severe ALI.The lung is also burn after systemic inflammatory response syndrome(SIRS)is one of the main target organs,has important clinical significance in prevention and treatment of burn injury with seawater immersion after acute lung injury,and the related research is rarely reported.In this study,20%TBSA deep II degree scalded rats with seawater immersion model,observe and aggravate the general rule of possible acute lung injury with seawater immersion after scald,provide a theoretical basis for the treatment of burn injury with seawater immersion,has a certain significance for combat readiness.Methods1?Animal model:108 SPF level Wistar rats weighted 180?220g were randomly divided into scald control group(groupA),scalded with freshwater immersion group(groupB),scalded with seawater immersion group(groupC).One day before scalded,hair on rats'back was depilated by 80g/L sodium sulfide.25g/L sodium amytal was injected into the abdominal cavity for anesthesia with the dosage of(35mg/kg)before scalded,then 20%TBSA deep second degree scald was made by immersing rats in 95? hot water for 12s.Except groupA,hands and feet of the rats were tied up and body below upper limbs in freshwater or seawater after scalded.After immersion,randomly selected 36 animals from groupA groupB or groupC with simple observation.2?Each group of experimental animals were soaked in 2H,4h,8h,respectively,in fresh and natural seawater.Each experimental group was randomly selected 12 animals were observed,before the death of the carotid artery blood gas analysis,blood samples were taken after the death of the lungs and lung tissue specimens.HE staining of lung tissue was performed to observe and compare the changes of lung morphology,inflammatory reaction and structural damage.Measurement of serum inflammatory factor ELISA method:measuring the proinflammatory mediators such as TNF-,IL-6,IL-8 alpha;proinflammatory mediators VEGF,high mobility group protein 1(HMGB-1),B cell colony promoting factor(PBEF),superoxide dismutase(SOD),propylene glycol(MDA),parallel analysis of artery the blood gas,including the determination of blood pH,Pa02,PaC02,and animal oxygen(Pa02/Fi 02)and the index calculation,immunohistochemical method(IHC)to observe the distribution of VEGF,PBEF and HMGB1 in lung tissue,to detect the expression of VEGF and PBEF protein in lung tissue by Western-Blot blotting.Detection of apoptosis rate of lung tissue by dUTP mediated in situ nick end labeling(TUNEL)method.3?All the data were showed in the form mean±SD,and analyzed by statistical software of SPSS 13.0.All dates were analyzed by factorial analysis of variance?One-way ANOVA,method of multiple comparisons between Group using LSD-t,P<0.05 as significance level.Results1?HE staining of lung tissue:A group of patients with injury after 2h,the presence of focal lymphocytic infiltration around the bronchi,most of the alveolar wall integrity,a small part of the collapse with a small amount of neutrophil infiltration.4h after injury,alveolar collapse,alveolar septum fibrinous exudation and infiltration of neutrophils,some alveolar red blood cells.8h after injury,part of alveolar structure intact,alveolar epithelial hyperplasia,alveolar cavity more neutrophil infiltration,some alveolar red blood cells;group B animal 2h after injury,part of alveolar wall integrity,multifocal alveolar collapse with neutrophil infiltration.4h after injury,alveolar cavity size and multifocal alveolar collapse,focal necrosis with neutrophil infiltration,karyorrhexis,some alveolar red blood cells,mild to moderate alveolar epithelial hyperplasia,alveolar fibrin exudation was seen.8h after injury,pulmonary alveolar cavity collapse,alveolar epithelial hyperplasia and multifocal lymphocytic infiltration around the bronchi,some alveolar red blood cells;group C animal 2h after injury,more focal lymphocytic infiltration around the bronchi,alveolar cavity has little fibrinous exudation,local alveolar septum infiltrated by a few scattered neutrophils,with alveolar cavity collapse.4h after injury,a small part of the alveolar structure intact,most alveolar collapse,alveolar septum see more fibrinous exudation and infiltration of neutrophils,alveolar space more red blood cell exudation and infiltration of neutrophils,multifocal lymphocytic infiltration around the bronchi.8h after injury,most alveolar collapse and disappearance of the normal alveolar structure,alveolar septum mass fibrinous exudation and neutrophil infiltration,part of alveolar space more red blood cell exudation and infiltration of neutrophils,multifocal lymphocytic infiltration around the bronchi.2?The changes of serum inflammatory factors:ELISA method of measuring each animal at each time point TNF-,IL-6,IL-8 alpha level;C group relative to the A group and B group,the levels of inflammatory cytokines IL-6,IL-8 and TNF-levels were significantly increased,the differences were statistically significant(P<0.05);and with seawater immersion time prolonged,C group of serum TNF-,IL-6 and IL-8 levels in Ming phase gradually increased,there were statistically significant differences(P<0.05);A group and B group by 22 comparing serum IL-6 and IL-8 levels difference at each time point after injury were not significant(P>0.05),the serum levels of TNF-two in group 2h after injury had no significant difference(P>0.05).3?The superoxide dismutase(SOD),propylene glycol(MDA)changes:ELISA method of measuring each animal at each time point serum MDA levels:C group relative to the A group and B group,the levels of MDA significantly increased,the differences were statistically significant(P<0.05);and with seawater immersion time prolonged,the serum level of MDA C group gradually increased,phase differences were statistically significant(P<0.05);each time point,the level of serum MDA in B group than in A group,the difference was statistically significant(P<0.05);each animal at each time point the levels of serum SOD in A group and C group relative;in B group,the levels of SOD were decreased,the differences were statistically significant(P<0.05);and with seawater immersion time,serum level of SOD in C group decreased gradually,phase differences were statistically significant(P<0.05);B SOD group at each time point of water There was significant difference in the level of A group(P<0.05).4?Each group of proinflammatory mediators VEGF,high mobility group protein 1(HMGB-1),B cell colony promoting factor(PBEF)changes:ELISA animal measured the levels of VEGF,HMGB-1,PBEF;C group relative to the A group and B group,the levels of VEGF,HMGB-1,PBEF water level increased significantly,the differences were statistically significant(P<0.05);and with seawater immersion time,C group,HMGB-1 serum VEGF and PBEF levels increased gradually during Ming,there were statistically significant differences(P<0.05);the serum levels of VEGF,B group HMGB-1,PBEF level is higher than that of A group.Each time,there were statistically significant differences between time points(P<0.05);immunohistochemical method(IHC)and Western-Blot blotting,PBEF and VEGF in lung tissue of HMGB1 distribution and expression of lung tissue in C group:VEGF,HMGB-1,PBEF protein significantly increased There was significant difference between A group and B group(P<0.05).5?DUTP in situ nick end labeling method(TUNEL method)to detect the apoptosis of lung tissue cells:cell apoptosis in the lung tissues of rats changed:C group relative to the A group and B group,the number of apoptosis of lung tissue cells increased significantly,and with the immersion time prolonged,gradually increasing the number of apoptosis of lung tissues,the difference was statistically significant(q=0.000 9L,0.00106,0.00049,P<0.01);A group and B group and see a few cells,no significant difference between the groups(q=0.01 1 0.0226,P<0.05).6?Arterial blood gas analysis and plasma osmotic pressure in each group at different time points:each animal at each phase point pH level;A group and B group,each time point pH levels showed no significant difference(P>0.05);2h after injury,C group and A group,the pH level of B group showed no significant difference(P>0.05)after injury;4H and 8h after injury in C group,A group,the relative pH levels of B group were decreased,there was significant difference(P<0.05),and with seawater immersion time,pH level of C group decreased gradually,phase differences were statistically significant(P<0.05);2H and 4h after injury.Pa02,A group and B group(Pa02/Fi 02)and oxygen index level showed no significant difference(P>0.05);after injury 8h,A group,Pa02(Pa02/Fi 02)and the oxygen index is higher than the level of group B,the difference had significant difference(P<0.05);each time point in C group than A group B,group Pa02,and oxygen index(Pa02/Fi 02)levels were significantly decreased,there was significant difference(P<0.05),and with seawater immersion time,C group Pa02,oxygen index(Pa02/Fi 02)levels decreased gradually,phase differences were statistically significant(P<0.05);and C group at 8h after injury,animal oxygen and finger the number of<300mmHg(Pa02/Fi 02),conforms to the standard of diagnosis of pulmonary dysfunction.C group relative to the A group and B group,the levels of PaC02 significantly increased,the differences were statistically significant(P<0.05);and with seawater immersion time,serum PaC02 level of C group increased gradually,when the phase differences were statistically significant(P<0.05);Plasma osmotic pressure changes:the same time point in C group plasma osmotic pressure were significantly higher than those in A group and B group,the differences were statistically significant(P<0.05);C group in different time points of plasma osmotic pressure with time gradually increased,the differences were statistically significant(P<0.05);Conclusion1.After scalding and immersing in seawater,the injury of lung was more serious than that of simple scald and immersion of fresh water after scalding.2.Seawater immersion caused serious systemic inflammation of lung tissue,lipid peroxidation damage and apoptosis of lung tissue cells in hypertonic environment,and metabolic acidosis may be an important mechanism for progressive lung injury in scalded rats.3.The degree of lung injury after immersion in seawater was significantly correlated with seawater immersion time.The greater the degree of injury was,the longer the immersion time was,which indicated that seawater immersion had a significant negative effect on lung function after burn.