Antimicrobial efficacy of composite irrigation solution against dominant pathogens in seawater immersion wound and in vivo wound healing assessment.

Seawater immersion wound is inevitably accompanied by bacterial infection. Effective irrigation is critical for bacterial infection prevention and wound healing. In this study, the antimicrobial efficacy of a designed composite irrigation solution against several dominant pathogens in seawater immersion wounds was evaluated, and in vivo wound healing assessment was conducted in a rat model. According to the time-kill result, the composite irrigation solution exhibits excellent and rapid bactericidal effect against Vibrio alginolyticus and Vibrio parahaemolyticus within 30 s of treatment while eliminating Candida albicans, Pseudomonas aeruginosa, Escherichia coli, and the mixed microbes after 1 h, 2 h, 6 h, and 12 h of treatment, respectively. Significant bacterial count reduction of Staphylococcus aureus was observed after 5 h treatment. In addition to its skin non-irritating attribute, the in vivo wound healing results further demonstrated that the irrigation solution showed high repair efficiency in the skin defect model inoculated with the mixed microbes. The wound healing rate was significantly higher than that of the control and normal saline groups. It could also effectively reduce the number of viable bacteria on the wound surface. The histological staining indicated that the irrigation solution could reduce inflammatory cells and promote collagen fibers and angiogenesis, thereby promoting wound healing. We believed that the designed composite irrigation solution has great potential for application in the treatment of seawater immersion wounds.

Study on an Animal Model of Seawater Immersion Injury Following Hemorrhagic Shock.

INTRODUCTION: To establish an animal model of delayed intravenous resuscitation following seawater immersion after hemorrhagic shock (HS). METHODS: Adult male SD rats were randomly divided into three groups: group NI (HS with no immersion), group SI (HS with skin immersion), and group VI (HS with visceral immersion). Controlled HS in rats was induced by withdrawing 45% of the calculated total blood volume within 30 min. In SI group, immediately after blood loss, 0.5 cm below the xiphoid process was immersed in artificial seawater, at (23 ± 1) °C, for 30 min. In VI group, the rats were performed by laparotomy and the abdominal organs were immersed in (23 ± 1) °C seawater for 30 min. Two hours after seawater immersion, the extractive blood and lactated Ringer's solution were delivered intravenously. The mean arterial pressure (MAP), lactate, and other biological parameters were investigated in different time points. The survival rate of 24 h after HS was recorded. RESULTS: After seawater immersion following HS, MAP and abdominal viscera blood flow decreased significantly, and the plasma levels of lactate and the organ function parameters were increased than the baseline. The above changes in VI group were more serious than those in SI and NI group, especially in myocardial and small intestine damage. The hypothermia, hypercoagulation, and metabolic acidosis were also observed after seawater immersion; the injury was more severely in VI group than that of SI group. However, the plasma levels of sodium, potassium, chlorine, and calcium in VI group were significantly higher than those before injury and in the other two groups. In the VI group, the level of plasma osmolality in instant, 2 h, and 5 h after immersion was 111%, 109%, and 108% of the SI group, respectively, all P < 0.01. The 24-h survival rate of VI group was 25%, which was significantly lower than that of SI group (50%) and NI group (70%), P < 0.05. CONCLUSIONS: The model fully simulated the key damage factors and field treatment conditions, reflected the effects of low temperature and hypertonic damage caused by seawater immersion on the severity and prognosis of naval combat wounds, and provided a practical and reliable animal model for the study of field treatment technology of marine combat shock.

Time-Varying Pattern and Prediction Model for Geopolymer Mortar Performance under Seawater Immersion.

In this study, immersion experiments were conducted on the geopolymer mortar (GPM) by using artificial seawater, and the effects of alkali equivalent (AE) and waterglass modulus (WGM) on the resistance of geopolymer mortar (GPM) to seawater immersion were analyzed. The test subjected 300 specimens to 270 days of artificial seawater immersion and periodic performance tests. Alkali equivalent (AE) (3-15%) and waterglass modulus (WGM) (1.0-1.8) were employed as influencing factors, and the mass loss and uniaxial compressive strength (UCS) were used as the performance evaluation indexes, combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the time-varying pattern of geopolymer mortar (GPM) performance with seawater immersion. The findings demonstrated a general trend of initially growing and then declining in the uniaxial compression strength (UCS) of geopolymer mortar (GPM) under seawater immersion. The resistance of geopolymer mortar (GPM) to seawater immersion decreased with both higher or lower alkali equivalent (AE), and the ideal range of alkali equivalent (AE) was 9-12%. The diffusion layer of the bilayer structure of the waterglass particle became thinner with an increase in waterglass modulus (WGM), which ultimately led to the reduction in the resistance of the geopolymer structure to seawater immersion. Additionally, a support vector regression (SVR) model was developed based on the experimental data to predict the uniaxial compression strength (UCS) of GPM under seawater immersion. The model performed better and was able to achieve accurate prediction within 1-2 months, and provided an accurate approach to predicting the strength of geopolymer materials in a practical offshore construction project.

Seawater immersion exacerbates the pathological changes caused by incisive corneal injury in rabbit eyes.

Background: Seawater immersion complicates injuries suffered during maritime conflicts and eye injury is one of most common injuries on the battlefield. This study aimed to delineate the pathophysiological changes in the cornea after corneal injury combined with seawater immersion. Methods: The left eye of New Zealand White rabbits was injured with firecracker and a 3-mm long whole-layer incision in the center of the cornea parallel to the corneal limbus, followed by seawater immersion. The right eye was used as a control. The histology of the cornea and the inflammatory cytokine/chemokine levels in the aqueous humor were examined on days 1 and 7 after injury. The protein levels of aquaporin 1, 3, and 5 were assessed by immunohistochemical staining 7 days after injury. The expression and activation of nuclear factor κB (NF-κB) were examined by Western blot analysis. Results: Seawater immersion exacerbated penetrating explosive injury caused progressive tissue damage of the cornea and ocular inflammation, with drastic increases in the expression of cytokines/chemokines in the aqueous humor, which was mediated by the upregulation and activation of NF-κB. Furthermore, corneal protein levels of aquaporin 1, 3, and 5 were significantly increased after incisive injury and seawater immersion. Conclusions: These data demonstrated that the combination of incisive injury and seawater immersion is a dangerous situation and effective care strategies should be developed for the management of such maritime injuries.

N-Acetyl-L-Cysteine Protects Organ Function After Hemorrhagic Shock Combined With Seawater Immersion in Rats by Correcting Coagulopathy and Acidosis.

Background: The mortality of trauma combined with seawater immersion is higher than that of land injury, however, research on how to treat this critical case and which treatments to adopt is lacking. Methods: The effect of the thiol compound, N-acetyl-L-Cysteine (NAC), on survival, acidosis, coagulopathy, vital signs, oxidative stress, and mitochondrial and multi-organ function was assessed in a rat model of hemorrhagic shock combined with seawater immersion (Sea-Shock). Results: Hemorrhagic shock combined with seawater immersion caused a severe lethal triad: multi-organ impairment, oxidative stress, and mitochondrial dysfunction. NAC (30 mg/kg) with lactated Ringer's (LR) solution (2 × blood volume lost) significantly improved outcomes compared to LR or hetastarch (HES 130/0.4) alone. NAC significantly prolonged survival time to 52.48 ± 30.09 h and increased 72 h survival rate to 11/16 (68%). NAC relieved metabolic acidosis and recovered the pH back to 7.33. NAC also restored coagulation, with APTT, PT, and PT-INR decreased by 109.31, 78.09, and 73.74%, respectively, while fibrinogen level increased 246.23% compared with untreated Sea-Shock. Administration of NAC markedly improved cardiac and liver function, with some improvement of kidney function. Conclusion: The addition of NAC to crystalloid resuscitation fluid alleviated oxidative stress, restored redox homeostasis, and provided multi-organ protection in the rats after Sea-Shock. NAC may be an effective therapeutic measure for hemorrhagic shock combined with seawater immersion.

Protective Effect of Moderate Hypotonic Fluid on Organ Dysfunction via Alleviating Lethal Triad Following Seawater Immersion With Hemorrhagic Shock in Rats.

Previous studies found that seawater immersion combined with hemorrhagic shock (SIHS) induced serious organ function disorder, and lethal triad was a critical sign. There were no effective treatments of SIHS. Fluid resuscitation was the initial measurement for early aid following hemorrhagic shock, while the proper fluid for SIHS is not clear. Effects of different osmotic pressures [lactated Ringer's (LR) solution, 0.3% saline, 0.6% saline, and 0.9% normal saline] on the lethal triad, mitochondrial function, vital organ functions, and survival were observed following SIHS in rats. The results showed that SIHS led to an obvious lethal triad, which presented the decrease of the body temperature, acidosis, and coagulation functions disorder in rats. Fluid resuscitation with different osmotic pressures recovered the body temperature and corrected acidosis with different levels; effects of 0.6% normal saline were the best; especially for the coagulation function, 0.6% normal saline alleviated the lethal triad significantly. Further studies showed that SIHS resulted in the damage of the mitochondrial function of vital organs, the increase of the vascular permeability, and, at the same time, the organ function including cardiac, liver, and kidney was disordered. Conventional fluid such as LR or 0.9% normal saline could not improve the mitochondrial function and vascular leakage and alleviate the damage of the organ function. While moderate hypotonic fluid, the 0.6% normal saline, could lighten organ function damage via protecting mitochondrial function. The 0.6% normal saline increased the left ventricular fractional shortening and the left ventricular ejection fraction, and decreased the levels of aspartate transaminase, alanine transferase, blood urea nitrogen, and creatinine in the blood. The effects of fluids with different osmotic pressures on the mean arterial pressure (MAP) had a similar trend as above parameters. The survival results showed that the 0.6% normal saline group improved the survival rate and prolonged the survival time, the 72 h survival rate was 7/16, as compared with the LR group (3/16). The results indicate that appropriate hypotonic fluid is suitable after SIHS, which alleviates the lethal triad, protects the mitochondrial function and organ functions, and prolongs the survival time.

Protective effects of valproic acid on cardiac and cerebral injury in rats subjected to severe scalding combined with seawater immersion injury with delayed fluid replacement / 中国药房

OBJECTIVE To study the protective effects o f valproic acid on cardiac and cerebral injury in rats subjected to severe scalding combined with seawater immersion injury with delayed fluid replacement. METHODS The rats were divided into scalding+delayed fluid replacement group （group S ），scalding+seawater immersion+delayed fluid replacement group （group SS ）， scalding+seawater immersion+valproic acid+delayed fluid replacement group （group SSV ）according to random number table ，with 60 rats in each group. All groups were subjected to 35％total body surface area third-degree full-thickness scalding with boiled water. Group SS and group SSV were immersed in artificial ；seawater（30 min）immediately after scalding ，and group SSV was subcutaneously injected with valproic acid 300 mg/kg immediately after out of water. Sodium lactate Ringer ’s 0314-2279277。E-mail：125467374@qq.com injection was injected intravenously within 30 minutes according to 1/2 Parkland formula at 2 h after scalding in each group for delayed fluid replacement. The death time of rats was recorded ，and the average survival time and 24 h survival rate of rats in each group were calculat ed. Mean arterial pressure （MAP），heart rate （HR），respiration rate （RR），rectal temperature （RT），arterial blood pH ，arterial partial pressure of oxygen （PaO2），arterial blood partial pressure of carbon dioxide （PaCO2），HCO3－，creatine kinase MB isoenzyme （CK-MB）and neuron specific enolase （NSE）were detected before scalding ，at 0，2，5 h after scalding. The pathological changes of cardiac and cerebral tissue were observed. RESULTS The 24 h survival rate of group SS （55％）was significantly lower than that of group S （90％）， while that of group SSV （75％）was increased significantly ，compared with group SS （P＜0.05）. Compared with group S ，the levels of MAP ，RT，HR，pH，PaO2 and HCO 3－ in group SS were significantly lowered ，while the levels of CK-MB and NSE were increased significantly at 0，2，5 h after scalding ；the levels of PaCO 2 were increased significantly at 2，5 h after scalding ， while the levels of RR were decreased significantly at 0，2 h after scalding （P＜0.05）. Compared with group SS ，the levels of MAP，RT，HR，pH，PaO2 and HCO 3－ in group SSV were significantly increased ，while the levels of PaCO 2，CK-MB and NSE were decreased significantly at 2，5 h after scalding ；the level of RR was increased significantly at 2 h after scalding （P＜0.05）. At 2，5 h after scalding ，cardiac and cerebral injury of rats in group SS were aggravated significantly than that in group S ；cardiac and cerebral injury of rats in group SSV were relieved significantly than that in group SS. CONCLUSIONS After severe scalding combined seawater immersion injury ，hypodermic injection of sodium valproate could protect cardiac and cerebral function of rats ， improve vital signs and blood gas index ，prolong survival time and improve survival rate in rats.

Microstructure and Properties of Poly(ethylene glycol)-Segmented Polyurethane Antifouling Coatings after Immersion in Seawater.

Polyurethane has a microphase separation structure, while polyethylene glycol (PEG) can form a hydrated layer to resist protein adsorption. In this paper, PEG was introduced to polyurethane to improve the antifouling properties of the polyurethane, providing a new method and idea for the preparation of new antifouling polyurethane materials. The mechanical properties, hydrophilicity, swelling degree, microphase separation and antifouling performance of the coatings were evaluated. The response characteristics of the polyurethane coatings in a seawater environment were studied, and the performance changes of coatings in seawater were tested. The results showed that the crystallized PEG soft segments increased, promoting microphase separation. The stress at 100% and the elasticity modulus of the polyurethane material also markedly increased, in addition to increases in the swelling degree in seawater, the water contact angle decreased. A total of 25% of PEG incorporated into a soft segment can markedly improve the antibacterial properties of the coatings, but adding more PEG has little significant effect. After immersion in seawater, the coatings became softer and more elastic. This is because water molecules formed hydrogen bonding with the amino NH, which resulted in a weakening effect being exerted on the carbonyl C=O hydrogen bonding and ether oxygen group crystallization.

Antibiotic-loaded chitosan-gelatin scaffolds for infected seawater immersion wound healing.

Skin damaged during sea battles is vulnerable to seawater immersion and bacterial infection. Scaffolds with effective biological function are highly desired for treatment of naval combat wound injuries. Herein, we prepared composite scaffolds of CS/GEL/GMs-CIP. The chitosan (CS) and gelatin (GEL) were cross-linked by genipin as matrix, and then gelatin microspheres loading ciprofloxacin hydrochloride (GMs-CIP) were add. From in vitro characterization results, CS/GEL/GMs-CIP had high water absorption ability, proper porosity, satisfactory fracture resistance, and flexibility. Furthermore, CS/GEL/GMs-CIP composite scaffold had excellent biocompatibility. Antibacterial experiments confirmed that CS/GEL/GMs-CIP had a significant inhibitory effect on E. coli, S. aureus and P. aeruginosa. The in vivo wound healing was evaluated using animal wound infection model of seawater immersion, and it was observed that the prepared composite scaffolds accelerated wound healing, reepithelialization, collagen deposition. Further analysis of wound tissue indicated that the expression of anti-inflammatory factor (TGF-ß1) was up-regulated, but the serum endotoxin levels and expression of pro-inflammatory factor (TNF-a, IL-6, and IL-1ß) were down-regulated. In summary, we believe that CS/GEL/GMs-CIP composite scaffold may serve as a promising multifunctional dressing for healing with open trauma wound infections and wound with seawater immersion.

Drifting away. Seawater survival and stochastic transport of the invasive Carpobrotus edulis.

Coastal areas are vulnerable and fluctuating habitats that include highly valuable spaces for habitat and species conservation and, at the same time, they are among the most invaded ecosystems worldwide. Occupying large areas within Mediterranean-climate coastlines, the "ecosystem engineer" Carpobrotus edulis appears as a menace for coastal biodiversity and ecosystem services. By combining the observation, current distribution, glasshouse experiment, and dispersion modeling, we aim to achieve a better understanding of the successful invasion process and potential dispersion patterns of C. edulis. We analyzed the response of plant propagules (seeds and plant fragments) to seawater immersion during increasing periods of time (up to 144 h). After 2 months of growth, plant fragments showed a total survival rate (100%) indicating high tolerance to salinity. During this time, fragment length was increased (up to 60%) and root length was higher than control in all cases. Also, immersed fragments consistently accumulated more biomass than control fragments. After two months of growth, photosynthetic parameters (Fv'/Fm', ΦNO, and ΦII) remained stable compared to control fragments. Physiologically, osmolyte and pigment content did not evidence significant changes regardless of immersion time. Based on the capacity of propagules to survive seawater immersion, we modeled the potential transport of C. edulis by combining an oceanic model (ROMS-AGRIF) with a particle-tracking model. Results indicated that propagules may travel variable distances maintaining physiological viability. Our model suggested that short-scale circulation would be the dominant process, however, long-scale circulation of propagules may be successfully accomplished in <6 days. Furthermore, under optimal conditions (southerly winds dominance), propagules may even travel large distances (250 km alongshore). Modeling transport processes, in combination with the dynamics of introduction and expansion, will contribute to a better understanding of the invasive mechanisms of C. edulis and, consequently, to design preventive strategies to reduce the impact of plant invasion.

Seawater Immersion Aggravates Early Mitochondrial Dysfunction and Increases Neuronal Apoptosis After Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major cause of death and disability in naval warfare. Due to the unique physiochemical properties of seawater, immersion in it exacerbates TBI and induces severe neural damage and complications. However, the characteristics and underlying mechanisms of seawater-immersed TBI remain unclear. Mitochondrial dysfunction is a major cause of TBI-associated brain damage because it leads to oxidative stress, decrease in energy production, and apoptosis. Thus, the present study aimed to further elucidate the current understanding of the pathology of seawater-immersed TBI, particularly the role of mitochondrial dysfunction, using a well-defined rat model of fluid percussion injury and a stretch injury model comprising cultured neurons. The biochemical and pathological markers of brain-related and neuronal injuries were evaluated. Histological analysis suggested that seawater immersion enhanced brain tissue injury and induced a significant increase in apoptosis in rats with TBI. Additionally, lactate dehydrogenase release occurred earlier and at higher levels in stretched neurons at 24 h after seawater immersion, which was consistent with more severe morphological changes and enhanced apoptosis. Furthermore, seawater immersion induced more rapid decreases in mitochondrial membrane potential, adenosine triphosphate (ATP) content, and H+-ATPase activity in the cortices of TBI rats. In addition, the immunochemical results revealed that seawater immersion further attenuated mitochondrial function in neurons exposed to stretch injury. The increases in neuronal damage and apoptosis triggered by seawater immersion were positively correlated with mitochondrial dysfunction in both in vivo and in vitro models. Thus, the present findings strengthen the current understanding of seawater-immersed TBI. Moreover, because seawater immersion aggravates mitochondrial dysfunction and contributes to post-traumatic neuronal cell death, it is important to consider mitochondria as a therapeutic target for seawater-immersed TBI.

Preparation of Antimicrobial Hyaluronic Acid/Quaternized Chitosan Hydrogels for the Promotion of Seawater-Immersion Wound Healing.

Wound immersion in seawater with high salt, high sodium, and a high abundance of pathogenic bacteria, especially gram-negative bacteria, can cause serious infections and difficulties in wound repair. The present study aimed to prepare a composite hydrogel composed of hyaluronic acid (HA) and quaternized chitosan (QCS) that may promote wound healing of seawater-immersed wounds and prevent bacterial infection. Based on dynamic Schiff base linkage, hydrogel was prepared by mixing oxidized hyaluronic acid (OHA) and hyaluronic acid-hydrazide (HA-ADH) under physiological conditions. With the addition of quaternized chitosan, oxidized hyaluronic acid/hyaluronic acid-hydrazide/quaternized chitosan (OHA/HA-ADH/O-HACC and OHA/HA-ADH/N-HACC) composite hydrogels with good swelling properties and mechanical properties, appropriate water vapor transmission rates (WVTR), and excellent stability were prepared. The biocompatibility of the hydrogels was demonstrated by in vitro fibroblast L929 cell culture study. The results of in vitro and in vivo studies revealed that the prepared antibacterial hydrogels could largely inhibit bacterial growth. The in vivo study further demonstrated that the antibacterial hydrogels exhibited high repair efficiencies in a seawater-immersed wound defect model. In addition, the antibacterial hydrogels decreased pro-inflammatory factors (TNF-α, IL-1ß, and IL-6) but enhanced anti-inflammatory factors (TGF-ß1) in wound. This work indicates that the prepared antibacterial composite hydrogels have great potential in chronic wound healing applications, such as severe wound cure and treatment of open trauma infections.

Numerical simulation for treatment of hypothermia based on vascular interventional direct heating system.

The treatment of hypothermia suffered by naval fighters owing to seawater immersion has been a focus of research in recent years. Currently, the treatment of hypothermia in China is limited to external rewarming, which is of low efficiency and is not effective for patients suffering moderate to severe hypothermia. We thus proposed a vascular interventional heating method which directly heats the blood flow via a minimally invasive heating needle for rewarming. And a numerical simulation using a compartment model based on finite difference method was conducted. A set of whole body heating treatment simulation was also developed. Appropriate treatment parameters and procedures can be set and adjusted based on patient physical parameters. Here temperature response curves of different heating modes were obtained and analyzed. It was demonstrated that the desired thermal response can be achieved by adjusting the heating power and heating time, ensuring controllable accuracy in the treatment of patients with severe hypothermia. The proposed treatment for hypothermia is a new and effective alternative, and further progress is expected in clinical trials.

Preparation of chitosan-collagen-alginate composite dressing and its promoting effects on wound healing.

The present study aimed to prepare a composite dressing composed of collagen, chitosan, and alginate, which may promote wound healing and prevent from seawater immersion. Chitosan-collagen-alginate (CCA) cushion was prepared by paintcoat and freeze-drying, and it was attached to a polyurethane to compose CCA composite dressing. The swelling, porosity, degradation, and mechanical properties of CCA cushion were evaluated. The effects on wound healing and seawater prevention of CCA composite dressing were tested by rat wound model. Preliminary biosecurity was tested by cytotoxicity and hemocompatibility. The results revealed that CCA cushion had good water absorption and mechanical properties. A higher wound healing ratio was observed in CCA composite dressing treated rats than in gauze or chitosan treated ones. On the fifth day, the healing rates of CCA composite dressing, gauze, and chitosan were 48.49%±1.07%, 28.02%±6.4%, and 38.97%±8.53%, respectively. More fibroblast and intact re-epithelialization were observed in histological images of CCA composite dressing treated rats, and the expressions of EGF, bFGF, TGF-ß, and CD31 increased significantly. CCA composite dressing showed no significant cytotoxicity, and favorable hemocompatibility. These results suggested that CCA composite dressing could prevent against seawater immersion and promote wound healing while having a good biosecurity.

Experimental study on water bath rewarming in rats with hypothermia by seawater immersion / 第二军医大学学报

Objective To observe the success rate and rewarming curve of different water bath rewarming in rats with severe seawater immersed hypothermia. Methods A total of 490 male SD rats were intraperitoneally implanted with temperature recorder before experiment, were randomly divided into immersion group (n=450) and control group (n=40). In immersion group 100 rats were immersed in (15.0±0.2) °C seawater for 2 h, 150 rats for 5 h, and 200 rats for 10 h. The survival rats of each group were randomly divided into five subgroups and given different rewarming treatments: passive rewarming (passive rewarming subgroup), 37 °C hot water bath rewarming for 0.5 h (37 °C active rewarming 0.5 h subgroup), 37 °C hot water bath rewarming for 1 h (37 °C active rewarming 1 h subgroup), 42 °C hot water bath rewarming for 0.5 h (42 °C active rewarming 0.5 h subgroup), 42 °C hot water bath rewarming for 1 h (42 °C active rewarming 1 h subgroup). The rats in the control group were without seawater immersion, and were randomized into four subgroups as above. The success rate of rewarming was calculated in each group. The serum levels of creatine kinase isoenzyme (CK-MB), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were determined in the survival rats after rewarming for 20 h. Dynamic intraperitoneal temperature was recorded at the end of the experiment, and then the passive rewarming velocity, delay afterdrop effect of hot water bath rewarming were calculated. Results With the prolongation of immersing time, the survival rate of rats was significantly decreased in the immersion group (P<0.05). The rewarming success rates were significantly decreased in both the passive and active rewarming groups (both P<0.05). The rewarming success rate in the 37 °C active rewarming 1 h subgroup was greater than or equal to other active rewarming subgroups and the passive rewarming subgroup. All rats in the control group survived after hot water bath. Compared with the control group, the serum levels of CK-MB, ALT and LDH were significantly increased in the surviving rats of the active rewarming subgroups with the prolongation of immersion time (P<0.05). At the same immersing time, the levels of CK-MB, ALT and LDH were significantly lower in the 37 °C active rewarming 1 h subgroup than those in the other active rewarming subgroups (P<0.05 for some results), and were lower than those in the passive rewarming subgroup (P<0.05 for some results). Rewarming curve showed that the rewarming velocity of the passive rewarming subgroup significantly decreased with the prolongation of immersing time (P<0.05), and the rewarming velocity of the dead rats was significantly lower than that of the surviving rats (P<0.05). Delayed afterdrop effect was found in abdominal temperature of hot water rewarming rats, and the greater the effect was, the higher the mortality rate was. The delayed afterdrop effect of 37 °C hot water bath was not obvious in the control group, but it was significantly obvious in 42 °C hot water bath subgroups (P<0.05). Conclusion The success rate of proper hot water bath rewarming is greater than that of passive rewarming in the treatment of severe seawater immersed hypothermia. Hot water bath can be used as a rewarming option in emergency situations, while improper rewarming conditions can decrease the treatment success rate, which may be related to the delayed afterdrop effect.

Efficacy of a new type of resuscitation solution on electrolyte imbalance in seawater immersion injured miniature pigs / 国际外科学杂志

Objective To study the effect of applying a new intravenous resuscitation solution to electrolyte imbalance in miniature pigs after seawater immersion injury.Methods A total of 20 Guizhou Ⅲ type miniature pigs aged 4 months were randomly divided to A and B groups,10 in each.The seawater immersion injury model was used to soak sea water for 3 hours.The changes of electrolytes in miniature pigs before and after soaking wererecorded.A group with intravenous infusion of 0.9％ sodium chloride solution,and B group with new type ofrecovery liquid intravenous rehydration.Electrolyte changes after infusion were recorded and analyzed.Data ofnormal distribution measurement data were expressed as ((x) ± s).The data of electrolyte before and after immersionwere analyzed by paired t test.After soaking,the relative data of electrolyte after sub-group rehydration wereanalyzed by independent sample t test.Results After seawater immersion,pH value were dropped from 7.39 ±0.06and 7.39 ±0.04 to 7.32 ±0.05 and 7.33 ±0.05,serum K + concentration elevated from (3.93 ±0.38) mmol/Land (3.93±0.42) mmol/L to (4.35 ±0.33) mmol/L and (4.37 ±0.14) mmol/L.Clconcentration increased from (93.38 ± 4.29) mmol/L and (92.88 ± 3.79) mmol/L to (102.80 ± 4.29) mmol/Land (103.50±2.46) mmol/L.Na+ concentration in serum were dropped from (140.64 ± 4.99) mmol/L and(140.69 ±4.72) mmol/L to (136.80 ±4.32) mmol/L and (136.90 ±3.03) mmol/L.After normal saline andnew type of recovery liquid rehydration respectively,group B with new recovery liquid,pH increased from 7.33 ±0.05 to 7.38 ±0.04 (P ＜0.05),serum concentration of K+ and Cl-concentration were dropped from (4.37 ±0.14) mmol/L and (103.50 ±2.46) mmol/L to (3.87 ±0.25) mmol/L and (94.15 ±4.23) mmol/L (P =0.005,P =0.007).The concentration of serum Na + back up from (136.90 ± 3.03) mmol/L to (139.30 ±3.06) mmol/L (P =0.038).A group of saline infusion after the various indicators did not change significantly.Conclusion The new intravenous resuscitation solution of miniature pigs electrolyte imbalance correction effect issignificant,that the resuscitation solution has some clinical value for seawater immersion iniurv.

Effects of hyperbaric oxygen therapy on open tibial fractures in rabbits after transient seawater immersion.

OBJECTIVE: To explore the effect and mechanism of hyperbaric oxygen (HBO2) therapy of open tibial fractures in rabbits after transient seawater immersion. METHODS: Forty-eight (48) New Zealand rabbits were randomly and averagely divided into an HBO2 therapy group (Group A) and a control group (Group B). All rabbits were subjected to unilateral open tibial fractures, while immersed in artificial seawater (20-22 °C) for three hours prior to debridement and external fixation. Group A was treated with HBO2 at 2 atmospheres absolute (ATA) for 50 minutes once daily for two weeks; Group B received postoperative routine treatments only. The fracture zone in each group was compared by radiological, histological and immunohistochemical examinations. RESULTS: In Group A, bony callus and mature osteocytes without infiltration of inflammatory cells were observed in the fracture zone. Vascular endothelial growth factor (VEGF) was expressed mainly in the cytoplasm of osteoblasts, chondrocytes and osteocytes, and exhibited significant changes at different time points. The gray value of bony callus in Group A was 190.58 ± 7.52; that of Group B was 144 ± 8.11. Difference between the groups was statistically significant (P ⟨ 0.01). The content of malondialdehyde (MDA) in Group A was significantly lower than Group B (P ⟨ 0.01), and the activity of superoxide dismutase (SOD) in Group A was higher than Group B (P ⟨ 0.01) at four weeks. There were no significant differences in MDA content and SOD activity between groups at eight and 12 weeks. CONCLUSIONS: HBO2 treatment of open tibial fractures in seawater can reduce the inflammatory reaction and reperfusion injury, and promote osteocytic proliferation and fracture healing.

[Effects of seawater immersion on the inflammatory response and oxygen free radical injury of rats with superficial partial-thickness scald at early stage].

Objective: To study the effects of seawater immersion on the inflammatory response and oxygen free radical injury of rats with superficial-thickness scald at early stage. Methods: Seventy Wistar rats were divided into healthy control group (HC, n=7), pure scald group (PS, n=21), scald+ fresh water immersion group (SF, n=21), and scald+ seawater immersion group (SS, n=21) according to the random number table. Rats in group HC did not receive any treatment, while 5% total body surface area superficial partial-thickness scald was made on the back of rats in the latter three groups. Rats in group PS lived freely immediately post burn, while wounds on the back of rats in groups SF and SS were immersed into fresh water and seawater, respectively. Serum and full-thickness skin tissue in the center of wounds on the back of 7 rats in groups PS, SF, and SS at post immersion (injury) hour (PIH) 2, 4, and 6 were collected, respectively, while serum and full-thickness skin tissue at the same position of the 7 rats in group HC were collected at PIH 6 of rats in other groups. Morphology of skin tissue was observed with HE staining; tumor necrosis factor-alpha (TNF-α) content in serum and skin tissue was determined by enzyme-linked immunosorbent assay; superoxide dismutase (SOD) content in serum and skin tissue was determined by hydroxylamine method; malondialdehyde content in serum and skin tissue was determined by thiobarbituric acid method. Data were processed with analysis of variance of factorial design, one-way analysis of variance, Welch test, LSD test, and Tamhane test. Results: (1) Epidermal cells of skin tissue of rats in group HC arranged in order and continuously, and the dermis tissue and accessory structures were clear and complete. The skin layer and epidermis of wounds of rats in group PS had no significant change, but the edema of epidermis and dermis and infiltration of inflammatory cells enhanced over time at PIH 2, 4, and 6. The horny layer of epidermis of wounds of rats in group SF reduced, and the edema of epidermis and dermis and infiltration of inflammatory cells enhanced over time at PIH 2, 4, and 6; some epidermal cells disintegrated at PIH 6. The horny layer of epidermis of wounds of rats in group SS significantly reduced, along with the increase in disintegration of epidermal cells, the significant enhancement of edema of epidermis and dermis, and infiltration of a large number of inflammatory cells over time at PIH 2, 4, and 6. (2) Compared with (247±27) pg/mL in group HC, the serum content of TNF-α of rats in group PS significantly increased at PIH 2 and 4 [respectively (675±122) and (367±54) pg/mL, P<0.05 or P<0.01] but significantly decreased at PIH 6 [(147±27) pg/mL, P<0.01]; the serum content of TNF-α of rats in group SF significantly decreased at PIH 6 [(90±24) pg/mL, P<0.01]; the serum content of TNF-α of rats in group SS significantly increased at PIH 2, 4, and 6 [respectively (1 646±58), (2 086±114), and (2 951±58) pg/mL, with P values below 0.01]. Compared with (364±123) U/mL in group HC, the serum content of SOD of rats in group PS significantly increased at PIH 2 and 4 [respectively (489±13) and (447±14) U/mL, with P values below 0.05]; the serum content of SOD of rats in group SF significantly decreased at PIH 6 [(282±13) U/mL, P<0.05]; the serum content of SOD of rats in group SS significantly increased at PIH 2 [(461±23) U/mL, P<0.05] but significantly decreased at PIH 4 and 6 [respectively (226±8) and (205±10) U/mL, with P values below 0.01]. Compared with that in group HC, the serum content of malondialdehyde of rats in groups PS, SF, and SS significantly increased at PIH 2, 4, and 6 (with P values below 0.01). (3) Compared with that in group HC, the TNF-α content in wound tissue of rats in groups PS and SS significantly increased at PIH 2, 4, and 6 (P<0.05 or P<0.01), and the TNF-α content in wound tissue of rats in group SF significantly increased at PIH 2 and 4 (with P values below 0.01). Compared with that in group HC, the SOD content in wound tissue of rats in groups PS and SF significantly increased at PIH 2, 4, and 6 (P<0.05 or P<0.01), and the SOD content in wound tissue of rats in group SS significantly increased at PIH 2 and 4 (with P values below 0.01). Compared with that in group HC, the malondialdehyde content in wound tissue of rats in groups PS, SF, and SS significantly increased at PIH 2, 4, and 6 (with P values below 0.01). Conclusions: Seawater immersion can enhance the inflammatory response and oxygen free radical injury of wounds and the whole body of rats with superficial partial-thickness scald at early stage.

Effect of vacuum sealing drainage on the expression of VEGF and miRNA-17-5p in seawater-immersed blast-injury wounds.

The aim of the present study was to compare and observe the expression levels of vascular endothelial growth factor (VEGF) and miRNA-17-5p during the treatment of seawater-immersed blast-injury wounds (SIBIW) under different conditions of vacuum sealing drainage (VSD), and to identify the optimized range of VSD treatment and partially explain its mechanisms. The bilateral hips and scapulae of experimental pigs (weight, 25-30 kg) were subjected to blast-injury wounds, followed by the seawater immersion. The animals then underwent conventional dressing treatment under 120, 180 and 240 mmHg VSD. Visual observation, in addition to histological, immunohistochemical and molecular biological techniques were applied to compare and observe the extent of wound healing and expression levels of VEGF and miRNA-17-5p. The wound healing of the VSD treatment group was improved compared with the control group, with 120 mmHg negative pressure producing the most marked effect. miR-17-5p expression was detected in the SIBIW granulation tissues. There was significant difference between each VSD treatment group and control group at each time point (P<0.05). Thus, the present results show that miR-17-5p can be expressed in SIBIW granulation tissues, and this effect is most evident under 120 mmHg negative pressure, which may inform the optimized negative range for the treatment of SIBIW.

Seawater immersion aggravates burn-associated lung injury and inflammatory and oxidative-stress responses.

With the increasing frequency of marine development activities and local wars at sea, the incidence of scald burns in marine accidents or wars has been increasing yearly. Various studies have indicated that immersion in seawater has a systemic impact on some organs of animals or humans with burn. Thus, for burn/scald injuries after immersion in seawater, it is desirable to study the effects and mechanisms of action on important organs. In the present study, we aimed to investigate the effect of immersion in seawater on lung injury, inflammatory and oxidative-stress responses in scalded rats. The structural damage to lungs was detected by hematoxylin and eosin staining and the results showed that seawater immersion aggravated structural lung injury in scalded rats. The expression of HMGB1 in lung tissues was detected by immunohistochemical analysis and the results showed that seawater immersion increased HMGB1 expression in lung tissues of scalded rats. Apoptosis in lung tissues was detected by terminal deoxynucleotidyl transfer-mediated dUTP nick end-labeling (TUNEL) staining and the results showed that seawater immersion increased apoptosis rate in lung tissues of scalded rats. In addition, the expression levels of TNF-α, IL-6, IL-8, SOD, and MDA in serum were analyzed by enzyme-linked immunosorbent assays (ELISAs) and the results showed that seawater immersion induced secretion of proinflammatory factors (TNF-α, IL-6, and IL-8), increased MDA protein level, and suppressed SOD activity in the serum of scalded rats. Furthermore, measurement of plasma volume and pH showed that seawater immersion decreased plasma volume and pH value. Overall, the results indicated that all effects induced by immersion in seawater in scalded rats are more pronounced than those induced by freshwater. In conclusion, seawater immersion may aggravate lung injury and enhance inflammatory and oxidative-stress responses after burn.