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.

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 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.

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.

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.

Pathophysiological process of traumatic vascular spasm in multiple crush injury

Despite recent advances in microsurgery, the incidence of thrombosis of repaired digital vessels following crush injury is higher than that of uncrushed arteries. The purpose of this study was to evaluate the effects of traumatic crush injury on uncrushed segments of artery adjacent to crushed segments. Sprague-Dawley rat-tail arteries were crushed for 1 hour by 30 pounds of force at two separate 3-mm-wide segments, with 10 mm of uncrushed artery between segments. Luminal size of the uncrushed segments decreased progressively over the first 12 hours, with a significant reduction by 4 hours postcrush. The condition of the arteries continued to deteriorate until, by 24 hours postinjury, they had been denuded of endothelium, and smooth muscle damage had occurred. Untreated vasospasm following a multiple-level crush injury therefore results in progressive endothelial and intimal damage and thrombosis in the intervening healthy uncrushed segments of artery. This article discusses the implications of these findings.

[Structural and functional changes of the loose connective tissue and macrophage system in experimental crush-syndrome]

Cells and the extracellular matrix of the loose connective tissue as well as the macrophage system were studied in experimental crush-syndrome in 50 rats using histological, histochemical and electron microscopical methods. The results of the investigation have shown that the components of the loose connective tissue and the macrophage system actively responded to 1-hour-long hindlimb compression. Severe structural and functional injury of the cells and extracellular matrix of the subcutaneous loose connective tissue and of the stroma of different organs (lung, heart, kidney) was detected on dayl, was especially pronounced on day 7 and partly regressed by day 30 after the decompression. These changes included the structural damage of fibroblasts, changes in the number and degranulation of the mast cells, inhibition of RNA synthesis in plasmoblasts and lymphoblasts and the destruction of the collagen, elastic and reticular fibers. The number of macrophages in the liver, lungs, spleen, lymph nodes was reduced on days 1 and 7 after the decompression, in some organs this effect persisted until day 20. The activity of acid phosphatase was reduced in the macrophages in crush-syndrome.

Medical experience of a university hospital in Turkey after the 1999 Marmara earthquake

OBJECTIVES

This study aimed to provide an overview of morbidity and mortality among patients admitted to the Hospital of the Medicine Faculty of Uludag University, Bursa, Turkey, after the 1999 Marmara earthquake.

METHODS

Retrospective analysis of the medical records of 645 earthquake victims. Patients' demographic data, diagnosis, dispositions, and prognosis were reviewed.

RESULTS

A total of 330 patients with earthquake related injuries and illness admitted to our hospital were included and divided into three main groups: crush syndrome (n = 110), vital organ injuries (n = 57), and non-traumatic but earthquake related illness (n = 55). Seventy seven per cent of patients were hospitalised during the first three days after the earthquake. The rate of mortality associated with the crush syndrome, vital organ injury, and non-traumatic medical problems was 21% (23/110), 17.5% (10/57), and 9% (5/55), respectively. The overall mortality rate was 8% (50/645).

CONCLUSIONS

In the first 24-48 hours after a major earthquake, hospital emergency departments are flooded with large numbers of patients. Among this patient load, those patients with crush syndrome or vital organ injuries are particularly at risk. Proper triage and prompt treatment of these seriously injured earthquake victims may decrease morbidity and mortality. It is hoped that this review of the challenges met after the Marmara earthquake and the lessons learned will be of use to emergency department physicians as well as hospital emergency planners in preparing for future natural disasters.

Early and vigorous fluid resuscitation prevents acute renal failure in the crush victims of catastrophic earthquakes

This study analyzes the effects of fluid resuscitation in the crush victims of the Bingol earthquake, which occurred in May 2003 in southeastern Turkey. Questionnaires asking about demographic, clinical, laboratory, and therapeutic features of 16 crush victims were filled in retrospectively. Mean duration under the rubble was 10.3 +/- 7 h, and all patients had severe rhabdomyolysis. Fourteen patients were receiving isotonic saline at admission, which was followed by mannitol-alkaline fluid resuscitation. All but two patients were polyuric. Admission serum creatinine level was lower than and higher than 1.5 mg/dl in 11 and 5 patients, respectively. Marked elevations were noted in muscle enzymes in all patients. During the clinical course, hypokalemia was observed in nine patients, all of whom needed energetic potassium chloride replacement. Four (25%) of 16 victims required hemodialysis. Duration between rescue and initiation of fluids was significantly longer in the dialyzed victims as compared with nondialyzed ones (9.3 +/- 1.7 versus 3.7 +/- 3.3 h, P < 0.03). Sixteen fasciotomies were performed in 11 patients (68%), nine of which were complicated by wound infections. All patients survived and were discharged from the hospital with good renal function. Early and vigorous fluid resuscitation followed by mannitol-alkaline diuresis prevents acute renal failure in crush victims, resulting in a more favorable outcome.

Production of consistent crush lesions in murine quadriceps muscle--a biomechanical, histomorphological and immunohistochemical study

Poor healing of high-energy fractures is often associated with severe muscle damage. This may be partly due to the production, by the injured muscle, of inflammatory cytokines that somehow misdirect bone healing. In order to investigate this question, an animal model was established which embodies a controlled degree of muscle injury with a dose response to the energy absorbed, that can be characterised histologically. Using a custom crush jig, 60 CFLP mice had either 100 or 200 g masses dropped from a fixed height onto the quadriceps muscle, with mechanical measurement of the impact. Energy of impact was reliably and significantly different between the small and large impact conditions, though there was more variability when the large mass was used. Animals were sacrificed at day 2, 4, 8, 16, and 24 post-injury. Muscle histomorphometry at all time points and immunohistochemistry for IL-1beta, IL-6, and TNF-alpha up to day 8 were used as measures of muscle damage, inflammation and repair. Histological sections were analysed into areas of normal muscle fibres, damaged/regenerating muscle fibres and fibrous/inflammatory infiltrate. Early histological response was similar between the two groups; the large crush group displayed significantly greater areas of inflammatory infiltrate and damaged muscle at the later time points after day 8. In the large crush group, IL-1beta and IL-6 expression were significantly higher at day 2 and TNF-alpha was higher at day 8 when compared to the small crush group. The experiment demonstrated that more severe injury to muscle was reliably followed by increased inflammatory cytokine production and a greater degree of inflammation and fibrosis. Increased production of inflammatory cytokines such as TNF-alpha and IL-1beta in the damaged muscles may activate macrophages and recruit fibroblasts, promote scar formation and lead to delayed union or non-union of the adjacent fracture(s).

Crush syndrome: estimating skeletal muscle damage by the rule of thirds

Since the early 1900s, CI and CS have been observed and reported. However, there has not been a method to rapidly determine the severity of CS based on the amount of SM damaged as the result of high-pressure forces exerted on the tissue. The amount of SM involved in the CI is directly proportional to the severity of the resulting CS. The severity of the CS dictates the level and complexity of care needed to best ensure patient survivability. Unlike surface burn injuries, where the "rule of nines" or the "rule of palm" are used to estimate the percentage of surface area involved, no such method has ever been presented for use in CS. In fact, there has been an attempt to use the "rule of nines" in CS patients. In developing a method to estimate percentage of SM involved in CS, it is hoped that retrospective studies can be performed to generate a workable model for treatment of CS patients.

[Morphological changes of tissues after extensive soft tissue injury]

OBJECTIVE

To study the pathological morphological changes for diagnosing the cause of death of extensive soft tissue injury or crush syndrome.

METHODS

The tissues were stained by HE and IHC.

RESULTS

(1) The Mb positive rate was 60%, 75%, 95% respectively. (2) Both the HSP70 positive rate of hearts and brains were 90%.

CONCLUSION

(1) The animal model of broad soft tissue injury was established. (2) Accumulated the pathological morphological data for diagnosing the cause of death of extensive soft tissue injury or crush syndrome.

[Fatal thoracic compression after being partially run over by an automobile]

The authors report on a fatal pedestrian accident in which the victim lay on the street and got under a car being run over by one of the front wheels. Both the car driver and the killed pedestrian were strongly alcohol-intoxicated at the time of the accident (2.45 a.m.). After the car had come to a standstill, the pedestrian remained trapped under the car until she was rescued by the fire brigade. On the basis of the autopsy findings and the technical expert opinion it could be reconstructed that the pedestrian's death was not caused by the consequences of being run over by the car, but by the subsequent compression of her thorax in the final accident position.

Regeneration and myogenic cell proliferation correlate with taurine levels in dystrophin- and MyoD-deficient muscles

This study coupled proton magnetic resonance spectroscopy (1H-NMR) and in situ hybridization plus autoradiography in a novel examination of different phenotypes of adult myogenesis that arise from genetic disruptions in mice. Study of muscle extracts from normal and dystrophin-deficient mdx limb and diaphragm muscles confirmed our previous findings linking taurine and muscle regeneration at the peak of damage and repair. 1H-NMR distinguished biochemical differences in regenerating muscles that were consistent with the extent of repair in three strains: mdx dystrophic mice; MyoD(-/-) mice that lack expression of the early myogenic regulatory gene MyoD; and a double-mutant mdx:MyoD(-/-) strain lacking expression of both MyoD and dystrophin. We tested the hypothesis that differences in spectra according to genotype and the regeneration phenotype are related specifically to proliferation by committed myogenic precursor cells. 1H-NMR distinguished the three mutant strains: Taurine was highest in mdx muscles, with the phenotype of most effective regeneration; lowest in MyoD(-/-) muscles, with the least effective formation of new muscle in repair, as reported previously; and intermediate in double-mutant muscles, now reported to show an intermediate repair phenotype. The early and late muscle precursors (mpcs) expressing myf5 and myogenin were examined for proliferation. Eighteen percent of mdx myf5-positive mpcs were proliferative, whereas myf5-positive mpcs did not proliferate in regenerating muscles that lacked MyoD expression. By contrast, whereas 30% of myogenin-positive mpcs were proliferative in mdx muscles, almost none were proliferative in MyoD(-/-) muscles, and 12% were proliferative in double-mutant muscles. Therefore, the extent of accumulated structural regeneration, taurine levels, and proliferation of late mpc (expressing myogenin) were congruent across genotypes. Proliferation by early mpc (expressing myf5) was inhibited by the lack of MyoD expression during muscle regeneration. These studies indicate the potential for 1H-NMR monitoring of muscle status in disease, regeneration, and treatment.

The effect of exposure time on microsurgical anastomoses of experimentally crushed arteries

Replantation after crushing amputation has a relatively low success rate. Although the mechanism of trauma is a major factor in failure, the time lapse before vessel anastomosis may also be a contributing factor. In this study, we observed the influence of the interval between vessel injury and surgical treatment on thrombus formation and healing after controlled crushing. Seventy-five Sprague-Dawley rats were used. A segment of femoral artery was clamped to create warm ischemia for 8 hours and crushed with a 15 kg load for one hour. After the loading device was removed the crushed segments were transected and the vessel ends exposed to the adjacent tissues and blood for 0, 2, 4 and 6 hours (groups II-V, respectively) prior to being anastomosed with standard microsurgical technique. The vessel samples were harvested at days 1, 2 and 7, respectively, and evaluated by light microscopy and scanning electron microscopy (SEM). The patency rate of the anastomoses was 97.3% at harvest and reendothelialization was completed at day 7. Three anastomoses with 4 or 6 hours exposure showed thrombosis, or clotting. The results indicated that up to 6 hours exposure time did not have a significant influence on thrombus formation or the healing process of vessels under the controlled conditions of this study.

[Pathology of crush syndrome]

Clinico-anatomical analysis of surgical material (32 cases) and 86 autopsy cases of myorenal syndrome (crush syndrome) is presented. Clinically in all cases there were symptoms of acute renal (hepatico-renal) failure which was a cause of death during the first 2 weeks. Septic complications were a cause of death at later periods. Grave alterations of traumatic, metabolic and septic origin were found in many organs in all cases. The sources of sepsis were decompressing longitudinal cuts and fasciotomies, shunts, lacerated wounds, catheters. Combined local treatment of wounds with sorbents, antibiotics, proteolytic enzymes, quantum therapy facilitated the destruction of bacteria and loss of their activity, wound purification and thus allowed coping with septic complications.

Crush syndrome following unconsciousness: need for urgent orthopaedic referral

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Catastrophic complication of simple cast treatment: case report

We report the case of a 36-year-old man who developed a compartment syndrome after a minor ankle fracture was casted. The treatment was inadequately monitored and he subsequently developed the manifestations of a crush syndrome. This case demonstrates that relatively minor injuries can indeed be fatal if appropriate vigilance is not maintained.

Tyre tread marks on the body without internal injuries

Two cases are presented involving a 5-year-old boy with tyre tread impressions on the back and right arm and a 4-year-old girl with tread marks on the head but both had no internal injuries. These cases suggest that injuries to internal organs do not always occur when the trunk or head is run over by the wheels of a vehicle.

[Homicide of a supervisor simulating an occupational accident]

An unusual case of homicide is reported. A driver of an excavator killed his foreman by using the scoops of his machine and tried to feign an industrial accident. The man was convicted by the autopsy findings because his testimony could not explain the severe injuries.

Cellular differences in the regeneration of murine skeletal muscle: a quantitative histological study in SJL/J and BALB/c mice

Skeletal muscle regeneration in SJL/J and BALB/c mice subjected to identical crush injuries is markedly different: in SJL/J mice myotubes almost completely replace damaged myofibres, whereas BALB/c mice develop fibrotic scar tissue and few myotubes. To determine the cellular changes which contribute to these differential responses to injury, samples of crushed tibialis anterior muscles taken from SJL/J and BALB/c mice between 1 and 10 days after injury were analysed by light and electron microscopy, and by autoradiography. Longitudinal muscle sections revealed about a 2-fold greater total mononuclear cell density in SJL/J than BALB/c mice at 2 to 3 days after injury. Electron micrographs identified a similar proportion of cell types at 3 days after injury. Autoradiographic studies showed that the proportions of replicating mononuclear cells in both strains were similar: therefore greater absolute numbers of cells (including muscle precursors and macrophages) were proliferating in SJL/J muscle. Removal of necrotic muscle debris in SJL/J mice was rapid and extensive, and by 6 to 8 days multinucleated myotubes occupied a large part of the lesion. By contrast, phagocytosis was less effective in BALB/c mice, myotube formation was minimal, and fibrotic tissue conspicuous. These data indicate that the increased mononuclear cell density, more efficient removal of necrotic muscle, together with a greater capacity for myotube formation in SJL/J mice, contribute to the more successful muscle regeneration seen after injury.

Macrophage activation decreases macrophage prostaglandin E2 release in experimental trauma

Prostaglandin E2 (PGE2) derived from macrophages following trauma may contribute to trauma-induced immunosuppression. This study evaluated the effect of glucan, a macrophage-activating agent, on macrophage PGE2 release in a murine trauma model. ICR/HSD mice were administered D5W, glucan pre-trauma, or glucan post-trauma, and subjected to hindlimb crush and amputation injury. Splenic macrophages were isolated 24 hours following trauma, cultured (24 hrs), and macrophage PGE2 levels were determined. In-vitro marrow proliferation was assessed as a measure of immune function. Crush-amputation injury increased (184%) macrophage PGE2 release. In contrast, glucan administration (pre or post) reduced PGE2 levels in macrophage supernatants (71% and 85%, respectively). A 52% decrease in in-vitro bone marrow proliferation was observed following trauma. Glucan pre- or post-trauma eliminated the suppression of bone marrow proliferation. In conclusion, macrophage-activating immunomodulators may exert beneficial effects following trauma by: 1) reducing macrophage PGE2 synthesis and release; and 2) reducing traumatic suppression of bone marrow proliferation.

[The mechanism and nature of the occurrence of compression injuries of the chest cavity in children and adults]

Comparative characteristic of thoracic injuries in children and adults due to compression gives evidence that value of ultimate rib strain when rib lesion occur is diminishing with age. Therefore the chest in adults (as compared to children) is more heavily injured in case of compression. For all this the character and localization of injuries depend on value of operating loads and make it possible to determine common mechanisms of thoracic frame deformations.

[Traumatic, ischemic and toxic rhabdomyolysis]

Rhabdomyolysis with myoglobinuria and acute renal failure can develop from a variety of traumatic and nontraumatic reasons and the clinical as well as forensic significance of it may vary from an epiphenomenon with an excellent prognosis to the cause of death. We present altogether four autopsy cases in two of which the rhabdomyolysis was associated with an acute intoxication with alcohol (male, 41 years of age) or amitriptyline in combination with chlordiazepoxide (male, 52 years of age). In both these subjects the myoglobinuria was a secondary finding and not the cause of death. In the other two subjects the outcome of rhabdomyolysis associated myoglobinuria was lethal. In the first one (female, 18 years of age) the muscle injury was traumatic, caused by long-lasting compression and ischaemia of the lower limbs (classical crush-syndrome), the outcome of which in spite of the adequate therapy was lethal. In the other one (male, 20 years of age) the rhabdomyolytic myoglobinuria and subsequent acute renal failure occurred postoperatively after reconstructive surgery of one hand and the interruption of blood circulation to the corresponding arm for the time of a nerve reconstruction. The recovery of the patient was complicated by continuing electrolyte disturbances associated with metastatic tissue calcification, especially of the lungs, leading to progressive respiratory insufficiency and eventually to death.

[Cellular composition of different zones in the rat and rabbit hepatic lobule under normal and experimental conditions]

Different types of hepatocytes (with caryopycnosis and caryolysis, at the state of mitosis, with amitotic nuclear strangulation and with two nuclei) were counted in the central, middle and peripheral zones of the hepatic lobule in rats subjected to an acute aminosin intoxication, and in rabbits after compressing soft tissues of the extremities. Time of observation--1--90 days in the rats and 10 h--20 days in the rabbits. In the zones of the hepatic lobule with the greatest degree of damage, the number of cells with caryopycnosis and caryolysis, as well as the number of hepatocytes with amitotic nuclear strangulation and binucleated cells were especially great. Mitotic activity of the hepatic cells was about 0.49% in the rats and 0.07% in the rabbits. Regardless the place of the damage in the hepatic lobule in all the zones, there was a definite correlation between the amount of cellular forms reflecting the demage and destruction of hepatocytes and their restoration, the same as observed in certain zones of the intact hepatic lobule.

[Electron- and light microscopic study of changes in the structure of the posterior hypophyseal lobe caused by long-term compression of soft tissues]

In 24 dogs light and electron microscopic changes of the neurohypohysis have been studied at early and intermediate periods of the prolonged compressing syndrom. The amount of neurosecrete has been stated to decrease considerably. Increased excretion of neurosecretory material from neurovascular zones is accompanied by mitochondrial swelling. Together with increased permeability of capillaries, disturbances in blood clotting system are demonstrated. With prolonged time of observations (intermediate period), further decrease of neurosecrete in axons and accumulating bodies is taking place. Some necrotic changes occur in endothelium.

[Damage to and regeneration of the kidney epithelium following crushing of the soft tissues of the extremities]

Dynamics of the cellular composition in the proximal thin, thick areas of the loop, distal portions and collective tubules of the kidney was studied in rabbits after crush of the soft tissues of the limb. Planimetric method was applied to determination of the area of the nuclear epithelium of the proximal, distal portions and the collective tubules. A relationship was revealed between the injury of the epithelium of the nephrons and the collective tubules and its restoration, and also an intensification of mitotic activity, elevation of the relative number of pathological mitoses, and increase of the mean size of the cell nuclei.

[Functional characteristics of light and dark cells]

Comparison of peculiarties attending the structure of mitochondria in the dark and light cells with the results of studying the respiration of condensed, intermediate and orthodoxic mitochondria showed that dark cells containing condensed mitochondria were at the state of rest or specific activity associated with a high level of bioenergetic and biosynthetic processes. Light cells with a preponderant content of intermediate mitochondria are characterized by the state of active specific activity accompanied by a high energy potential, intensified energy expenditure and a reduction of the level of biosynthetic processes. Light cells with a prevalence of orthodoxic mitochondria are characterized by a low level of energy provision and a predominance of the processes of decomposition of structures over their resynthesis.