Ferroptosis in acute kidney injury following crush syndrome: A novel target for treatment.

BACKGROUND: Crush syndrome (CS) is a kind of traumatic and ischemic injury that seriously threatens life after prolonged compression. It is characterized by systemic inflammatory reaction, myoglobinuria, hyperkalemia and acute kidney injury (AKI). Especially AKI, it is the leading cause of death from CS. There are various cell death forms in AKI, among which ferroptosis is a typical form of cell death. However, the role of ferroptosis has not been fully revealed in CS-AKI. AIM OF REVIEW: This review aimed to summarize the evidence of ferroptosis in CS-AKI and its related molecular mechanism, discuss the therapeutic significance of ferroptosis in CS-AKI, and open up new ideas for the treatment of CS-AKI. KEY SCIENTIFIC CONCEPTS OF REVIEW: One of the main pathological manifestations of CS-AKI is renal tubular epithelial cell dysfunction and cell death, which has been attributed to massive deposition of myoglobin. Large amounts of myoglobin released from damaged muscle deposited in the renal tubules, impeding the normal renal tubules function and directly damaging the tubules with oxidative stress and elevated iron levels. Lipid peroxidation damage and iron overload are the distinguishing features of ferroptosis. Moreover, high levels of pro-inflammatory cytokines and damage-associated molecule pattern molecules (HMGB1, double-strand DNA, and macrophage extracellular trap) in renal tissue have been shown to promote ferroptosis. However, how ferroptosis occurs in CS-AKI and whether it can be a therapeutic target remains unclear. In our current work, we systematically reviewed the occurrence and underlying mechanism of ferroptosis in CS-AKI.

Immunomodulatory role of recombinant human erythropoietin in acute kidney injury induced by crush syndrome via inhibition of the TLR4/NF-κB signaling pathway in macrophages.

Objective: The present study aimed to investigate whether recombinant human erythropoietin (rHuEPO) plays an immunomodulatory function by regulating the TLR4/NF-κB signaling pathway.Materials and methods: C57BL/6 mice were intraperitoneally injected with rHuEPO and, half an hour later, with 50% glycerol at the dose of 7.5 ml/kg to induce crush syndrome (CS)-acute kidney injury (AKI). The levels of TNF-α, IL-1ß, IL-6, serum creatinine (Scr), and creatine kinase (CK) were measured. The kidney tissues were analyzed by HE staining, and macrophage infiltration was detected by immunohistochemistry. Double immunofluorescence staining, RT-qPCR, and western blotting were conducted to analyze TLR4/NF-κB p65 expression. Ferrous myoglobin was co-cultured with RAW264.7 cells to mimic crush injury and the production of proinflammatory cytokines. The expression levels of TLR4 and NF-κB p65 were measured.Results: In vivo study results revealed that rHuEPO ameliorated renal function, tissue damage, production of proinflammatory cytokines, and macrophage infiltration in the kidneys. The protein and mRNA expression levels of genes involved in the TLR4/NF-κB signaling pathway in CS-induced AKI mice were upregulated (p < .05). Meanwhile, the expression levels of TLR4, NF-κB p65, and proinflammatory cytokines in RAW264.7 cells were downregulated in CS-AKI mice injected with rHuEPO (p < .05).Conclusions: Our results demonstrated the immunomodulatory capacity of rHuEPO and confirmed that rHuEPO exerts protective effects against CS-induced AKI by regulating the TLR4/NF-κB signaling pathway in macrophages. Therefore, our findings highlight the therapeutic potential of rHuEPO in improving the prognosis of CS-AKI patients.

Ipsilateral radial nerve, median nerve, and ulnar nerve injury caused by crush syndrome due to alcohol intoxication: A case report.

RATIONALE: Autologous peripheral nerve injury caused by crush syndrome due to alcohol intoxication is relatively rare, and to our knowledge, the compression of 3 upper limb nerves at the same time has not been reported previously. If a compressive peripheral nerve injury is not treated in a timely manner, it is difficult to recover neurological function, and the prognosis is poor. PATIENT CONCERNS: Here, we present a case of a 50-year-old man with ipsilateral radial nerve, median nerve, and ulnar nerve injuries caused by autogenous compression after drunkenness. DIAGNOSIS: Electromyography and nerve conduction studies suggested peripheral nerve injury in the left upper limb. The diagnosis was injury to the radial nerve, median nerve, and ulnar nerve in the left upper arm. INTERVENTIONS: Exploratory neurolysis surgery of the radial nerve, median nerve, and ulnar nerve was performed in the left upper arm. Postoperative oral neurotrophic drugs were administered, and functional exercise was performed. OUTCOMES: After timely diagnosis and treatment, the strength of the left upper arm muscle recovered, and the prognosis of neurological function was satisfactory during 3 years of follow-up sessions. LESSONS: In the treatment of such patients, a comprehensive understanding of their medical history and a strict physical examination should be performed. Combined with neuroelectrophysiological and imaging examination, the diagnosis can be confirmed. After timely diagnosis and treatment, the prognosis is mostly excellent.

A novel method to assess the severity and prognosis in crush syndrome by assessment of skin damage in hairless rats.

PURPOSE: Crush syndrome (CS), a serious medical condition characterised by damage to the muscle cells due to pressure, is associated with high mortality, even when patients receive fluid therapy during transit to the hospital or admission to the hospital. There is no standard triage approach for earthquake victims with crush injuries due to the scarcity of epidemiologic and quantitative data. We examined whether mortality can be predicted based on the severity of skin damage so that assess the severity and prognosis in crush syndrome by assessment of skin damage in hairless rats because we have previously observed that CS results in oedema and redness of the skin in rats. METHODS: Anaesthetised rats were subjected to bilateral hind limb compression [1 kg (mild) and 2 kg (severe) loads] with a rubber tourniquet for 5 h. The rats were then randomly divided into three groups: sham, mild CS, and severe CS. RESULTS: The mild and severe CS groups had mortality rates of 20 and 90%, respectively. The severe CS group demonstrated higher rates of hyperkalaemia, hypovolemic shock, acidosis, and inflammation. Skin damage was significantly worse in the severe CS group compared to the mild CS group. Skin damage showed good correlation with pathological severity. CONCLUSIONS: Skin damage is a valid measure of transepidermal water loss and severity of CS. We suggest that these models may be useful to professionals who are not experienced in disaster management to identify earthquake victims at high risk of severe CS.

Macrophage extracellular trap formation promoted by platelet activation is a key mediator of rhabdomyolysis-induced acute kidney injury.

Rhabdomyolysis is a serious syndrome caused by skeletal muscle injury and the subsequent release of breakdown products from damaged muscle cells into systemic circulation. The muscle damage most often results from strenuous exercise, muscle hypoxia, medications, or drug abuse and can lead to life-threatening complications, such as acute kidney injury (AKI). Rhabdomyolysis and the AKI complication can also occur during crush syndrome, an emergency condition that commonly occurs in victims of natural disasters, such as earthquakes, and man-made disasters, such as wars and terrorism. Myoglobin released from damaged muscle is believed to trigger renal dysfunction in this form of AKI. Recently, macrophages were implicated in the disease pathogenesis of rhabdomyolysis-induced AKI, but the precise molecular mechanism remains unclear. In the present study, we show that macrophages released extracellular traps (ETs) comprising DNA fibers and granule proteins in a mouse model of rhabdomyolysis. Heme-activated platelets released from necrotic muscle cells during rhabdomyolysis enhanced the production of macrophage extracellular traps (METs) through increasing intracellular reactive oxygen species generation and histone citrullination. Here we report, for the first time to our knowledge, this unanticipated role for METs and platelets as a sensor of myoglobin-derived heme in rhabdomyolysis-induced AKI. This previously unknown mechanism might be targeted for treatment of the disease. Finally, we found a new therapeutic tool for prevention of AKI after rhabdomyolysis, which might rescue some sufferers of this pathology.

Anti-high mobility group box-1 (HMGB1) antibody attenuates kidney damage following experimental crush injury and the possible role of the tumor necrosis factor-α and c-Jun N-terminal kinase pathway.

BACKGROUND: Inflammation plays a crucial role in kidney damage after crush syndrome (CS). Several researchers report that high mobility group box-1 protein (HMGB1) may be the vital trigger in kidney damage, and tumor necrosis factor-α (TNF-α) and c-Jun N-terminal kinase (JNK) are involve in this pathophysiological process, but their biological roles are unclear. This study aimed to explore the relationship between HMGB1, JNK, and TNF-α in kidney damage. METHODS: The crush injury model was established using weight compression. The reliability of the crush injury model was determined by hematoxylin-eosin (HE) staining. Western blot was used to detect the expression of HMGB1, JNK, and TNF-α, and TUNEL was used to mark apoptotic cells in the renal cortex. RESULTS: The results showed that the highest expression of HMGB1 in muscle was 12 h after CS. JNK and TNF-α increased and peaked at 1 day after CS in kidneys. Western blot analysis revealed that anti-HMGB1 antibody could downregulate the expression of JNK and TNF-α. Anti-TNF-α could downregulate activation of JNK, and SP600125 could downregulate expression of TNF-α in the kidneys. In addition, anti-HMGB1 antibody, anti-TNF-α antibody, and SP600125 could reduce cellular apoptosis in the renal cortex. CONCLUSIONS: It is possible that JNK and TNF-α commonly contribute to kidney damage by assembling a positive feedback cycle after CS, leading to increased apoptosis in the renal cortex. HMGB1 from the muscle may be the trigger.

A historical perspective on crush syndrome: the clinical application of its pathogenesis, established by the study of wartime crush injuries.

Crush syndrome is a fine example of how pathology can play a direct role in revealing the best treatment and management for diseases. It can occur when crush injuries are sustained. Skeletal muscle becomes damaged under the weight of a heavy object, and victims experience severe shock and renal failure. The discovery of the pathology of crush syndrome belongs to two individuals: Seigo Minami and Eric Bywaters. They separately helped to define the pathogenesis of crush syndrome during World Wars I and II. Seigo Minami is believed to have been the first to record the pathogenesis of crush syndrome. In 1923, he described the cases of three soldiers who died of renal failure caused by crush injury during World War I. Using microscopic studies to investigate the pathology of their kidneys, he found the soldiers had died due to 'autointoxication' caused by rhabdomyolysis. This discovery was not known to Eric Bywaters, who described crush syndrome in 1941, having studied victims of the London Blitz during World War II. He defined the 'autointoxication' as the release of rhabdomyolysis products via reperfusion. He therefore established the need for emergency fluid replacement to treat crush syndrome. The findings made by Minami and Bywaters highlight a remarkable achievement in clinical pathology, despite the adversity of war. It is these findings on which current guidelines are based. By reviewing their work, it is hoped that the role of pathology can be better appreciated as a valuable resource for delineating the treatment and management of diseases.

Improved angiogenesis and healing in crush syndrome by fibroblast growth factor-2-containing low-molecular-weight heparin (Fragmin)/protamine nanoparticles.

BACKGROUND: We produced fibroblast growth factor (FGF)-2-containing low-molecular-weight heparin (Fragmin)/protamine nanoparticles (FGF-2 + F/P NPs). The purpose of this study was to evaluate the effectiveness of the local administration of FGF-2 + F/P NPs on repairing crush syndrome (CS)-injured lesions after compression release using a nonlethal and reproducible CS injury rat model. MATERIALS AND METHODS: The hind limbs of the anesthetized rats were compressed for 6 h using 3.6 kg blocks, as previously described. The effects of administering FGF-2 + F/P NPs (group A), F/P NPs alone (group B), FGF-2 alone (group C), and saline (control; group D) were examined. Motor function, surface blood flow in the hind limbs, and the wet/dry weight ratio in the tibialis anterior muscle were examined for 1-28 d after the compression release. Histologic analyses were also performed. RESULTS: At the middle and late stages (3-28 d after the compression release), group A had higher scores in the motor function, improved blood flow, increased number of blood vessels, and faster recovered muscle tissue, compared with the other groups. There was no significant difference in enhanced edema in the tibialis anterior muscle among all groups. CONCLUSIONS: The local administration of FGF-2 + F/P NPs to a CS-injured lesion was effective in repairing damaged muscle tissue after compression release.

Comparison of two fluid solutions for resuscitation in a rabbit model of crush syndrome.

BACKGROUND: Crush syndrome is a common injury, the main characteristics of which include acute kidney injury. However, there is still lack of reliable animal model of crush syndrome, and it also remains controversial as to which type of fluid should be chosen as a more appropriate treatment option for prevention and treatment of acute kidney injury. METHODS: The rabbits were crushed at the lower limbs for 6 h with 36 times the body weight, which means the pressure of each leg was also 36 times the body weight. Fluid resuscitation was performed from 1 h prior to the end of the crush treatment until 24 h after the reperfusion. Tissue, blood and urine samples were collected at predetermined time points before and after reperfusion. Twelve rabbits in each group were taken for survival observation for 72 h. RESULTS: The model group showed elevated serum creatine kinase, aspartate aminotransferase, alanine aminotransferase, and K(+) level, reduced serum Ca(2+) level and Na(+) level, and increased serum creatinine and blood urea nitrogen levels, neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 (p < 0.05). The 0.9 % normal saline (SAL) group and SAL plus 6 % hydroxyethyl starch 130/0.4 SAL/HES group showed reduced serum creatinine and blood urea nitrogen levels (p < 0.05). The SAL/HES group also showed reduced serum IL-6 and IL-10 levels (p < 0.05). The 72 h survival rate of the SAL/HES group was higher than that of the model group (p < 0.05). CONCLUSION: The rabbit model of crush syndrome showed clinical features consistent with those of crush syndrome. There was no significant difference in the ability of preventing AKI after a crush injury between the two fluid solutions, while SAL/HES can improve the survival rate.

[Preliminary study on the pathogenic mechanism of myoglobin-induced endoplasmic reticulum stress and apoptosis in crush syndrome].

OBJECTIVE: To explore the pathogenic mechanism of myoglobin-induced endoplasmic reticulum stress (ERS) and apoptosis in tubular epithelial cells in acute kidney injury (AKI) mouse model of crush syndrome. METHODS: Eighteen C56BL/6 mice were randomly divided into control group, modeling 8 h group and modeling 24 h group. The AKI model of crush syndrome was established by intramuscular injection of 50% glycerol saline solution into thigh (8 microL/g), while equivalent volume of physiological saline was injected in control group. AKI was diagnosed when serum creatinine (sCr) level increased to double value of control group. The mice in the experimental groups were sacrificed at the time points of 8 h and 24 h after injection respectively. Serum Cr was detected and renal tissues was observed under electron microscopy. Apoptosis was detected by TUNEL technique. Marker proteins and mRNA of apoptosis and ERS were detected by immunohistochemistry and real-time PCR. Human kidney proximal tubular cell (HK-2) cells cultured in vitro were randomly divided into control, intervention 6 h and intervention 12 h groups. Control group were incubated in standard cell culture (DMEM/F12) and the two intervention groups were incubated in special DMEM/F12 in which ferrohemoglobin was added. After 6 h and 12 h incubation, the cells were collected and apoptosis was detected by flow cytometry. RESULTS: AKI model of crush syndrome was successfully established, which was proved with sCr doubling at the 8 h after the intramuscular injection of glycerol saline. Swelling of endoplasmic reticulum and mitochondria in proximal tubular epithelial cells was more obvious in the two model groups than that in control group. TUNEL staining showed the percentage of positive cells in AKI groups was higher than that in control group (P<0.05). Immunohistochemistry and real-time PCR showed the expressions of caspase3, caspase12 and CHOP in AKI groups were higher than those in control group (P<0.05). Flow cytometry showed cell apoptosis ratio was higher in model groups than control groiap (P<0.05). CONCLUSION: Myoglobin induced ERS and apoptosis may be involved in the pathogenesis of AKI in crush syndrome.

Forklift-Related Crush Injuries of the Foot and Ankle.

BACKGROUND: Forklift-related crush injuries of the foot and ankle are relatively common in cities with shipping and construction industries. There is a paucity of literature on the incidence and sequelae of such injuries. We aimed to describe the incidence, patterns of injuries, sequelae, and morbidity associated with this type of injury. METHODS: A retrospective review of all patients with forklift-related crush injuries of the foot and ankle for 4 years was conducted. Patients' demographics, mechanisms and patterns of injury, fracture type, compartment syndrome, number of reconstructive operations, operative details, length of hospital stay, medical leave, repeat evaluation in emergency room, and complications were recorded and analyzed. RESULTS: There were 113 (2.17%) patients with forklift-related crush injuries out of 5209 patients seen in our institution for injuries of the foot and ankle. Crush injury from the wheels of the forklift truck was the most common mechanism at 71 (62.8%) patients. The forefoot was the most commonly injured region, followed by the midfoot, hindfoot, and ankle, with almost one-third (28.3%) of the patients having multiple injuries to the foot. Nine (8%) had open fractures, while 5 (4.4%) had compartment syndromes. Forty (35.4%) patients required hospitalization, and 35 (87.5%) of those hospitalized required operative intervention. Those who had surgery were more likely to have complications compared with those who did not require operative intervention (16 [45.7%] of 35 patients vs 7 [9%] of 78 patients; P < .05) and more likely to require longer medical leave (mean, 183 vs 30 days, P < .05). CONCLUSION: Forklift-related crush injuries of the foot and ankle are increasingly common in industrialized cities. The forefoot is commonly affected with involvement of multiple regions. Up to one-third of affected patients required hospitalization and multiple operative interventions resulting in loss of productivity, income, and significant morbidity. The possibility of residual disabilities must be clearly defined to the patients and their employers to manage potential workplace limitations and long-term expectations. LEVEL OF EVIDENCE: Level IV retrospective case series.

Improved survival rate by temperature control at compression sites in rat model of crush syndrome.

BACKGROUND: Crush syndrome (CS) has been reported in disasters, terrorist incidents, and accidents, and the clinical and pathologic picture has gradually been clarified. Few lethal and reproducible animal models of CS with use of a quantitative load are available. A new model is needed to investigate pathologic and therapeutic aspects of this injury. MATERIALS AND METHODS: Using a device built from commercially available components, both hindlimbs of anesthetized rats were respectively compressed for 6 h using 3.6-kg blocks. The effects of trunk warming alone without compressed hindlimbs (Group A), non-warming at room temperature (Group B), whole-body warming including compressed hindlimbs (Group C), or warming of compressed hindlimbs alone (Group D) during compression were examined. Survival rates were compared and hematological and histologic analyses were performed at specific time points after compression release. RESULTS: Limb or whole-body warming significantly worsened the survival of rats. We found a much lower survival rate of 0%-10% in animals, in which the hindlimbs were warmed during compression (Groups C and D) at 12 h after compression release, compared with 90%-100% in animals without warming of the hindlimbs (Groups A and B). Groups C and D showed significantly enhanced hyperkalemia at ≥4 h after compression release and all blood samples from dead cases showed hyperkalemia (>10 mEq/L). CONCLUSIONS: We developed a new lethal and reproducible rat CS model with a quantitative load. This study found that warming of compressed limbs worsened the survival rate and significantly enhanced hyperkalemia, apparently leading to cardiac arrest.

Oxidative stress may be involved in distant organ failure in tourniquet shock model mice.

Crush syndrome is characterized by prolonged shock resulting from extensive muscle damage and multiple organ failure. However, the pathogenesis of multiple organ failure has not yet been completely elucidated. Therefore, we investigated the molecular biological and histopathological aspects of distant organ injury in crush syndrome by using tourniquet shock model mice. DNA microarray analysis of the soleus muscle showed an increase in the mRNA levels of Cox-2, Hsp70, c-fos, and IL-6, at 3h after ischemia/reperfusion injury at the lower extremity. In vivo staining with hematoxylin and eosin (HE) showed edema and degeneration in the soleus muscle, but no change in the distant organs. Immunohistological staining of the HSP70 protein revealed nuclear translocation in the soleus muscle, kidney, liver, and lung. The c-fos mRNA levels were elevated in the soleus muscle, kidney, and liver, displaying nuclear translocation of c-FOS protein. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis suggested the involvement of apoptosis in ischemia/reperfusion injury in the soleus muscle. Apoptotic cells were not found in greater quantities in the kidney. Oxidative stress, as determined using a free radical elective evaluator (d-ROM test), markedly increased after ischemia/reperfusion injury. Therefore, examination of immunohistological changes and determination of oxidative stress are proposed to be useful in evaluating the extent of tourniquet shock, even before changes are observed by HE staining.

Restraint stress aggravates rat kidney injury caused by a crush injury through endoplasmic reticulum stress.

BACKGROUND: The present study aimed to determine whether restraint stress aggravates kidney injury caused by a crush injury through endoplasmic reticulum stress (ERS). METHODS: In this study, Sprague-Dawley rat restraint stress, crush injury, and stressful injury models consisting of restraint stress and crush injury were established. An ERS inhibitor, Salubrinal (Sal), was administered intraperitoneally 30 minutes before induction of daily injury in the stressful injury group. At the end of the experimental procedures, plasma levels of noradrenaline and adrenaline, creatine phosphokinase, creatinine, and blood urea nitrogen were measured. Kidneys were harvested, and paraffin-embedded sections of kidney tissues were processed for hematoxylin-eosin staining and TUNEL assay to verify pathologic changes. Western blot was used to determine the protein levels of glucose-regulated protein 78, CCAAT/enhancer-binding protein-homologous protein, caspase 12, caspase 3, and MCP-1 in kidney specimens. RESULTS: Compared with crush injury, the most significant changes in kidney injury occurred in the stressful injury group, which was inhibited by Sal. The results suggested that restraint stress aggravates kidney injury caused by a crush injury, and the mechanism might involve ERS. Further study showed that double attacks induced a significant increase in the levels of glucose-regulated protein 78, CCAAT/enhancer-binding protein-homologous protein, caspase 12, and caspase 3, which was inhibited by Sal. The same changes were observed using the TUNEL assay. Double attacks also induced an increased expression of the proinflammatory cytokine, MCP-1, which was inhibited by Sal. CONCLUSION: Apoptosis and inflammation induced by ERS are important mechanisms by which restraint stress aggravates kidney injury caused by a crush injury.

Mouse model of muscle crush injury of the legs.

Because crush injury to skeletal muscle is an important cause of morbidity in natural disaster and battlefield settings, a reproducible and refined animal model of muscle crush injury is needed. Both open and closed small-animal models of skeletal muscle crush injury are available but are limited by their need for surgical isolation of the muscle or by the adverse effect of fibular fracture, respectively. In the current study, we developed and validated a novel, noninvasive mouse model of lower-extremity muscle crush injury. Despite the closed nature of our model, gross evidence of muscle damage was evident in all mice and was verified microscopically through hematoxylin and eosin staining. The injury elicited both neutrophil and macrophage infiltration at 24 and 48 h after injury. The area percentage and mean antigen area of F4/80-positive macrophages were higher at 48 h than at 24 h after injury, and CD68-positive macrophage area percentage and mean antigen area differed significantly between injured and uninjured muscle. In addition, the incidence of fibular fracture was one third lower than that reported for an alternative noninvasive model. In conclusion, our model is a reproducible method for muscle crush injury in the mouse pelvic limb and is a refinement of previous models because of its decreased bone fractures and reduction of animal numbers.

[Experimental study on establishment of a simple model of rats crush injury-crush syndrome].

OBJECTIVE: To establish a repeatable, simple, and effective model of rat crush injury and crush syndrome. METHODS: A total of 42 female Sprague Dawley rats (2-month-old, (CS) so as to lay a foundation for further study on CS. weighing 160-180 g) were divided randomly into the control group (n=6) and experimental group (n=36). The rats of the experimental group were used to establish the crush injury and CS model in both lower limbs by self-made crush injury mould. The survival rate and hematuria rate were observed after decompression. The biochemical indexes of blood were measured at 2, 4, 8, 12, 24, and 48 hours after decompression. The samples of muscle, kidney, and heart were harvested for morphological observation. There was no treatment in the control group, and the same tests were performed. RESULTS: Seven rats died and 15 rats had hematuria during compression in the experimental group. Swelling of the lower limb and muscle tissue was observed in the survival rats after reperfusion. The liver function test results showed that the levels of alanine transaminase and aspartate aminotransferase in the experimental group were significantly higher than those in the control group (P < 0.05). The renal function test results showed that blood urea nitrogen level increased significantly after 2 hours of decompression in the experimental group, showing significant difference when compared with that in the control group at 12, 24, and 48 hours after decompression (P < 0.05); the creatinine level of the experimental group was higher than that of the control group at 4, 8, 12, and 24 hours, showing significant difference at 8, 12, and 24 hours (P < 0.05). The serum K+ concentration of the experimental group was higher than that of the control group at all time, showing significant difference at the other time (P < 0.05) except at 2 hours. The creatine kinase level showed an increasing tendency in the experimental group, showing significant difference when compared with the level of the control group at 4, 8, 12, and 24 hours (P < 0.05). The histological examination of the experimental group showed that obvious edema and necrosis of the muscle were observed at different time points; glomeruli congestion and swelling, renal tubular epithelial cell degeneration, edema, necrosis, and myoglobin tube type were found in the kidneys; and myocardial structure had no obvious changes. CONCLUSION: The method of the crush injury and CS model by self-made crush injury mould is a simple and effective procedure and the experimental result is stable. It is a simple method to establish an effective model of rats crush injury and CS.

Impact of traumatic muscle crush injury as a cause of cardiomyocyte-specific injury: an experimental study.

BACKGROUND: Muscle crush injury commonly occurs after earthquakes, collapse of buildings and sjambok beatings, and it often induces crush syndrome if not treated promptly. The general manifestation of crush syndrome is the presence of myoglobinuria with acute renal failure. However, whether cardiomyocyte injury is induced after muscle crush injury has not been investigated. The aim of this study was to observe the effects of muscle crush injury on cardiomyocyte injury and its relationship to the changes of ANP and ET-1 levels after muscle crush injury in rats. METHODS: Muscle crush injury was produced in Male Sprague-Dawley rats. Forty-eight rats were divided into six groups. The changes of electrocardiogram (ECG) were recorded. The serum levels of K(+), Ca(2+), urea, creatinine (CR), creatine kinase (CK), creatine kinase-myocardial band (CK-MB) and cardiac troponin I (cTnI) were detected by automated biochemical analysis and automated chemiluminescence assay, respectively. The myocardial and plasma levels of ANP and ET-1 were investigated by radioimmunoassay. Myocardial apoptosis and caspase-3 protein expression were quantitatively analysed by TUNEL-staining and Western blotting, respectively. RESULTS: After six hours of decompression, the serum levels of K(+) and urea increased and ST-segment elevated and heart rates decreased pronouncedly over 48h, CR increased and Ca(2+) decreased considerably over 24h. The serum levels of CK-MB and cTnI increased significantly from 6h to 24h and CK increased markedly from 0h to 24h after decompression and then decreased slowly. However, after 48h of decompression, the serum levels of cTnI were still higher than those of the control group. Plasma levels of ANP and ET-1 increased and myocardial ANP and ET-1 decreased progressively over 48h, and changed significantly from 6h to 48h after decompression. The number of TUNEL-positive myocytes and caspase-3 protein expression were higher from 6h to 48h after decompression. Moreover, the levels of K(+), urea, CR, CK, CK-MB, cTnI and caspase-3 reached their highest values after 12h of decompression. There were significant correlations between the plasma ANP elevation and the myocardial ANP decline, between the plasma ANP elevation and the plasma ET-1 increase, and between the plasma ET-1 increase and the myocardial ET-1 decline. CONCLUSIONS: Cardiomyocyte injury was induced by muscle crush injury at the early stage of decompression but not at compression. The most dangerous period of cardiomyocyte injury was at the 12th hour of decompression. Cardiomyocyte injury may partly relate to the changes of ANP and ET-1.

Sivelestat improves outcome of crush injury by inhibiting high-mobility group box 1 in rats.

Severe crush injury is associated with high mortality because of resulting hyperkalemia in early phase and multiorgan dysfunction in later phase. In this study, we investigated the effects of sivelestat administration 1 h before reperfusion on the outcome of crush injury. Crush injury was induced by 6 h of direct compression to both hindlimbs of anesthetized rats with blocks weighing 3.5 kg each side, followed by 3 h of reperfusion. Rats were randomly assigned to three groups. In the control group, rats were infused with normal saline at 1 mL/kg per hour throughout the experiment without compression. Rats in the positive control group were compressed for 6 h, followed by fluid resuscitation initiated 1 h before release with normal saline. The infusion rate was increased from 1 to 10 mL/kg per hour and continued for 4 h. Rats in the treated group underwent the same procedures as in the positive control group, but sivelestat was added to normal saline (concentration was adjusted to infuse 10 mg/kg per hour) during fluid resuscitation (for 4 h). Treatment with sivelestat significantly improved survival rate with P = 0.032. This was accompanied by lower serum high-mobility group box 1 (HMGB1) levels after 3-h reperfusion, attenuated lung injury (assessed using hematoxylin-eosin stain), and suppression of HMGB1 expression in the lung and the liver. These results suggest that treatment with sivelestat improves the outcome of crush injury, likely by inhibiting HMGB1 in rats.