Characteristics and mechanisms of extremity injuries caused by mine blasts in shoals.

BACKGROUND: The characteristics of explosion in water are different from those in air and vary in different water depths. It is important to investigate the characteristics and mechanisms of extremity injuries caused by mine blasts in shoals. METHODS: A total of ninety New Zealand rabbits were randomly divided into four groups put in different depths of water (land group, midpoint of the thigh in the shoal 1 group, the xiphoid process in the shoal 2 group, and control group). Electric detonators simulating mines were placed under the rabbits' right hindpaw. After detonation, the animals were subjected to morphological examination. RESULTS: The lower third of the calf was almost completely destroyed by the mine blast on land, and only the rabbits' feet and ankles were destroyed in shoals. The skeleton, artery and sciatic nerve were injured more seriously in shoals than those on land. CONCLUSION: Mine blasts in shoals caused less disruption of the soft tissue than those on land. However, the skeleton was more seriously damaged in shoals since the pressure wave was transmitted with greater intensity and had a stronger shattering effect on the skeleton. Furthermore, the characteristics of extremity injuries varied according to water depths.

Lung injury following lower extremity blast trauma in rats.

BACKGROUND: Lower extremity blast trauma is a common injury during armed conflict and after terrorist attacks with a high mortality, which is likely associated with distant vital organ injury. The current study aimed to investigate the underlying mechanisms of remote lung injury after blast lower extremity trauma. METHODS: Sprague-Dawley rats were randomly divided into two groups: sham and blast. The blast group underwent blast trauma to the left hind limb using chartaceous electricity detonators, which was then subdivided into the time at which they were sacrificed: 0.5, 1, 3, and 6 hours. The sham group was also subdivided into the baseline control and time course groups. The baseline group was sacrificed 0.5 hours after artery cannulation and the time course at 6 hours after sham blast. The lungs were harvested for histologic analysis and water content measurement. Blood samples were harvested at each end of experiment and analyzed for cytokines, myeloperoxidase, malondialdehyde, and superoxide dismutase and cystathionine γ-lyase activity and hydrogen sulfide. RESULTS: Blast hind limb trauma induced alveolar injury and cell infiltration, together with an increase in lung water content, in a time-dependent manner. Plasma and lung levels of proinflammatory cytokines, tumor necrosis factor-α and interleukin 6, and malondialdehyde, were found to be significantly increased in conjunction with a rise in myeloperoxidase and a concurrent fall in superoxide dismutase, cystathionine γ-lyase, and hydrogen sulfide. CONCLUSION: Our data demonstrated that blast limb trauma causes remote lung injury, which is likely associated with remarkable inflammatory response, oxidative stress, and depletion of protective mechanisms.

Low- and high-dose hydrogen peroxide regulation of transcription factor NF-E2-related factor 2.

BACKGROUND: Reactive oxygen species (ROS) may play both physiological and pathophysiological roles. Transcription factor NF-E2-related factor 2 (Nrf2) regulates antioxidant response element (ARE)-mediated genes expression and coordinates induction of chemoprotective proteins in response to physical and chemical stresses. The exact role of Nrf2 in cellular responses to different levels of oxidative stresses remains unknown. METHODS: Rat pulmonary microvascular endothelial cells were cultured and treated with 0 mmol/L, 0.125 mmol/L, 0.25 mmol/L, 0.5 mmol/L, 1.0 mmol/L and 2.0 mmol/L hydrogen peroxide solution for 2 hours. Nrf2 gene expression was assayed by reverse transcription-PCR, Nrf2-ARE binding activity was assayed with electrophoretic mobility shift assay (EMSA), and localization of Nrf2 was detected with immunohistochemistry. RESULTS: Low and moderate (0.125 mmol/L, 0.25 mmol/L and 0.5 mmol/L) doses hydrogen peroxide exposure of rat pulmonary microvascular endothelial cells led to the nuclear accumulation of Nrf2, increased activity of transcription regulation and up-regulation of ARE-medicated gene expression. In contrast, high doses of hydrogen peroxide (1 mmol/L, 2 mmol/L) exposure of the cells led to the nuclear exclusion of Nrf2, decreased activity transcription regulation and down-regulation of ARE-mediated gene expression. CONCLUSION: Low and moderate doses of hydrogen peroxide play protective roles by increasing transcription activity of Nrf2, whereas high- dose hydrogen peroxide plays a deleterious role by decreasing transcription activity of Nrf2.

[Effect of substance P on the migration and differentiation of cultured epidermal stem cells to hair follicle in vitro].

OBJECTIVE: To investigate the effect of substance P (SP) on the migration and differentiation of epidermal stem cells (ESCs) to hair follicle, and its mechanism. METHODS: ESCs were cultured in vitro, and confirmed by positive staining of K19 and integrin beta1 with immunohistochemistry. SP was added into the culture of ESCs which were labelled with 5-BrdU, and the cell cultures were divided into control, 10(-5) mol/L SP, 10(-6) mol/L SP, and 10(-7) mol/L SP groups according to the different doses of SP addition. Cell suspension (0.3 ml) containing SP was injected into the dermis in the back of nude mice. Repeated injection of the equal amount of cell suspension in the same place was carried out on 4, 7, 10 and 14 days after first injection. The cells in control group received the same treatment but without SP. The skin specimens in the area of cell culture injection and the normal skin remote from cell injection were harvested for the histological examination and hair follicle counting by immunohistochemistry and electronmicroscope 28 days after injections. RESULTS: Hair follicles in scattered distribution were observed in 10(-5) mol/L SP group,but some of them were defective in development. Hypoplasic hair follicle and a few hair follicles with distinct structure were observed in 10(-5) mol/L SP group. Large amounts of hair follicles with distinct structure in deep dermis and subcutaneous tissue were observed in 10(-6) mol/L SP, 10(-7) mol/L SP groups, and some of them showed positive staining of brown BrdU in the hair root, and most of them showed positive staining of brown beta-catenin, but a few of them showed developmental defect. In contrast, hypoplasia of hair follicle underneath epidermis and deep layer of dermis with positive staining of brown BrdU and beta-catenin in epidermis were observed in control group. The number of hair follicles in 10(-6)mol/L SP, 10(-7) mol/L SP groups [(1.9 +/- 1.2 ), (1.3 +/- 0.8)] was obviously less than that in control group [(10. 5 +/- 1.2), P < 0.01]. CONCLUSION: SP can induce ESCs to migrate from the basal layer into hair follicle, and this effect is dependent on the SP concentration. SP can also elevate the expression of beta-catenin in ESCs,which induces its differentiation to hair follicles.

Surgical treatment for rabbits' femoral arteries subjected to gunshot wounds combining with seawater immersion.

OBJECTIVE: To investigate the surgical treatment methods and evaluate the outcome of gunshot wounds combining with seawater immersion in rabbits' femoral arteries. METHODS: One hundred healthy New Zealand white rabbits (either sex, 3.14 kg+/-0.61 kg in weight) were randomly divided into a seawater immersion group (n=50) and a simple injury group (n=50). The unilateral femoral arteries of all the rabbits were injured by 0.38 g steel spheres with velocity of 600-800 m/s fired by a 7.62 mm rifle. The rabbits in the seawater immersion group were immersed in seawater (saline content of 2.54%, pH 8.2-8.4, and at 21 degrees C) for 60 minutes but those in the simple injury group were not. After the injured segment (observed by naked eyes) of the femoral artery was excised, the blood flow restoration was reconstructed by direct end-to-end anastomosis, reversed autogenous venous grafting or cryopreserved arterial allografting, according to the length of the arterial defects. At 24 hours, and 7, 14 and 21 days after operation, the blood flow was examined. Operative exploration was performed for the animals with partly or fully obstructed blood flow. The tissues around the anastomosis sites and the grafts were harvested for pathological observation under a light microscope and an electron microscope. RESULTS: In the rabbits with completely transected injury, the unobstructed rates in the first 3 weeks after operation were 80.00% in the seawater immersion group and 86.67% in the single injury group, and no significant difference was found between the two groups (P>0.1). In the rabbits with arterial contusion injury, the unobstructed rates in the first 3 weeks after operation were 86.67% in the seawater immersion group and 82.35% in the single injury group, and no significant difference was found between the two groups (P>0.1). Most thrombosis occurred in the first operative week. Atypical endothelial cells were detected at the anastomosis sites at the first operative week, and the anastomosis sites were lined with endothelial cells in 3 weeks postoperatively. CONCLUSIONS: During the surgical treatment for gunshot wounds combining with seawater immersion, resection of the grossly-injured artery and routine artery reconstruction can obtain satisfactory outcome. Homologous artery is a kind of vascular graft with certain applied value.

Comparative study on effects of burn-blast combined injury and burn-firearm combined injury complicated with seawater immersion on vascular endothelial cells.

OBJECTIVE: To comparatively study the effects and mechanisms of burn-blast combined injury and burn-firearm combined injury complicated with seawater immersion on vascular endothelial cells. METHODS: A total of 40 healthy adult hybrid dogs of both sexes, weighing 12-15 kg, were used in this study. Randomly-selected 20 dogs were established as models of burn-blast combined injury (the burn-blast injury group) and the other 20 dogs as models of burn-firearm combined injury (the burn-firearm injury group). Then the wounds of all the dogs were immediately immersed in seawater for 4 hours, and then they were taken out from the seawater. Blood samples were withdrawn from the central vein of the dogs before injury, and at 4, 7, 10, 20, and 28 hours after injury to measure the circulating endothelial cells and the von Willebrand factor. RESULTS: Circulating endothelial cells increased significantly at 4 hours after injury in all the dogs. But they reached peak at 7 hours after injury in the burn-blast injury group and at 28 hours after injury in the burn-firearm injury group. The changes of circulating endothelial cells in the burn-blast injury group were significantly different from those in the burn-firearm injury group at 4, 7, 20, and 28 hours after injury (P < 0.01). The von Willebrand factor reached peak at 4 hours after injury in the burn-blast injury group and at 28 hours in the burn-firearm injury group. The changes of von Willebrand factor in the burn-blast injury group were significantly different from those in the burn-firearm injury group at 4, 20, and 28 hours after injury (P < 0.01). CONCLUSIONS: In burn-blast injury combined with seawater immersion, the vascular endothelial cells changed most significantly at 4 hours or 7 hours after injury, while burn-firearm injury combined with seawater immersion have the same at 20 hours or 28 hours after injury.

Pathological study of rabbits' femoral arteries subjected to gunshot wounds combining with seawater immersion.

OBJECTIVE: To investigate pathological characteristics of gunshot wounds concomitant seawater immersion in rabbits' femoral arteries. METHODS: Thirty rabbits were divided randomly into 3 groups: simple gunshot-wound group (Group I, n = 10), gunshot wound with seawater immersion for 30 mins (Group II, n = 10), and 60 mins group (Group III, n = 10). Femoral arteries were impacted by 0.38 g steel spheres fired with a 7.62 mm rifle. After being wounded, rabbits in Groups II and III were immersed in seawater for 30 or 60 mins, but those in Group I were not. At 2, 4, 6, 8, 12 hours following injury, a 40 mm segment of the artery on each side of the gunshot point were excised and observed by light and electron microscopy. RESULTS: The patterns of arterial injuries were mainly contusion and transection. Completely transected artery was classified as primary-wound-tract area, contused area and shocked area. Compared with those in Group I, the primary-wound-tract and contused areas in Group II manifested obvious swelling in the arterial wall especially at the outside 2/3 of the media. Vacuolar structures were often seen in smooth muscle cells of the media. Intercellular space among the smooth muscle cells were filled with homogeneous acidophilic substances. Deep rugae among endothelial cells flattened or rugal folds lost their longitudinal orientation, and marked fibrin and platelet deposition were noticed. No significant difference was detected between Group II and III. The pathological changes in the shocked area were similar in 3 groups. CONCLUSIONS: For gunshot wounds concomitant seawater immersion in rabbits' femoral arteries, there was a marked swelling of cells and intercellular space in primary-wound-tract area and contusion area. The influence of these pathological changes on surgical reparation deservers further study.

[Changes in neuropeptide substance P and calcitonin gene-related peptide in scarless wound healing in fetal rabbit skin].

OBJECTIVE: To explore the role of the neuropeptide in fetal scarless wound healing. METHODS: The animal models were replicated in which a full-thickness wound was inflicted on the back of rabbit fetuses at 22 days gestation (term=31 days). The progress of wound healing was observed on micro-and macro-levels at the 1 st, 2 nd, 3 rd, 5 th, 7 th, 14 th post-injury days respectively. The expression level of substance P(SP) and calcitonin gene-related peptide (CGRP) during wound healing was assessed by immunohistochemistry staining. RESULTS: The cutaneous wounds in fetal rabbits healed more rapidly than that in adult and without the formation of scar. The expression of SP and CGRP of wound decreased in fetal rabbit at the early stage post-injury, down to the lowest levels on the 2 nd post-injury day (75%, 80%, vs. fetal control, both P<0.01), then increased gradually, up to the normal levels. The expression of SP and CGRP of wound decreased in adult rabbit at the early stage post-injury, down to the lowest levels on the post-injury 1 st day (60%, 76%, vs. adult control, both P<0.01), then increased quickly, up to a higher level than normal group, reaching the peak on the post-injury 7th day(168%, 126%, vs. adult control, both P<0.01), then returned to the normal levels. CONCLUSION: The low level of neuropeptide may contribute to scarless wound healing in fetal rabbit.

[Comparison of resuscitation with Parkland formula and with improved protocol on hemodynamics in projectile-burn combined wound in dogs with seawater immersion].

OBJECTIVE: To compare hemodynamic effects of resuscitation with Parkland formula or with the improved protocol on projectile-burn combined wound in dogs with seawater immersion. METHODS: A model of projectile-burn combined wound in dogs with seawater immersion was reproduced, and 20 dogs were randomized into three groups: projectile-burn combined wound with seawater immersion (immersion group, n=8), Parkland formula resuscitation (lactated Ringer's solution 4 ml/kg per 1%total body surface area for 24 hours, standard resuscitation group, n=6), and improved protocol groups (lactated Ringer's solution 2.5 ml/kg per 1% total body surface area colloid solution 6% hetastarch 0.5 ml/kg per 1% total body surface area for 24 hours, improved group, n=6). Changes of hemodynamics and central temperature (CT) before injury, and 4, 7, 10, 20 and 28 hours after injury were observed. The mortality was observed. RESULTS: After resuscitation with Parkland formula, CT as well as hemodynamic indexes and amount of urine were improved, but central venous pressure (CVP) and the amount of urine were higher in early period of resuscitation. CVP was (14.7+/-3.1)cm H2O and the amount of urine was (2.38+/-0.18)ml.h(-1).kg(-1) at 7 hours after injury. Hemodynamics was not stable during later period of experiment. After resuscitation with the improved protocol, the hemodynamics ameliorated better than resuscitation with Parkland formula. No animals died in improved group, but 4 and 1 died respectively in immersion group and standard resuscitation group. CONCLUSION: Fluid resuscitation according to the improved protocol is more suitable for projectile-burn combined wound in dogs with seawater immersion than resuscitation with Parkland formula.

[Effects of substance P on granulation tissue fibroblasts proliferation and expression of basic fibroblast growth factor mRNA].

OBJECTIVE: To explore the proliferation-promoting effect of sensory neuropeptide substance P (SP) on the cultured granulation tissue fibroblasts in vitro and its regulative effect on the gene expression of basic fibroblast growth factor (bFGF) mRNA. METHODS: The proliferation-promoting effect of cultured granulation tissue fibroblasts was observed by means of MTT; the regulative effect of SP on gene expression of fibroblast bFGF by RT-PCR. The time and dose-efficiency relations were also observed. RESULTS: There was a significant proliferation-promoting effect of SP on the cultured granulation tissue fibroblasts in vitro in a remarkable dose-dependent fashion. However, bFGF antibody only partly exerted its inhibitive effect. SP could induce the bFGF mRNA expression of the fibroblasts at the 3rd and 6th hour (P < 0.01). SP could promote the bFGF mRNA expression of the fibroblasts in the concentration of 10(-9) - 10(-5) mol/L and peaked in the concentration of 10(-7) mol/L. CONCLUSIONS: SP has a significant proliferation-promoting effect on the granulation tissue fibroblasts, which is correlated with SP inducing bFGF mRNA expression of fibroblasts.

[Effect of sensory neuropeptide substance P on the differentiation of cultured epidermal stem cells in vitro].

OBJECTIVE: To investigate the effect of sensory neuropeptide substance P (SP) on the differentiation of cultured epidermal stem cells (ESC) in vitro,with in vitro cultured ESC as the platform. METHODS: ESC from newborn Wistar rats were isolated, purified by repeated passages in culture. SP was added for stimulation when ESC clone grew. Immunohistochemistry staining with K14 antibody, and flow cytometry (FCM) was performed at 0, 24th, 48th, 72nd, 96th, 144th, 192nd, 240th, 288th, 336th, 384th, 432nd post differentiation hours (PDH) to identify the cell groups and to detect if there were transient amplifying cells (TAC) among the cells. RESULTS: ESC in culture formed large colonies after SP treatment with positive staining for K14, indicating that they were TACs. The results of FCM indicated that when ESC were stimulated by SP, TAC colony formation occurred and the cell number increased in a constant speed. CONCLUSION: ESC could differentiate into TAC by neuropeptide SP induction, and the number of ESC kept on a certain level during the process.

Effect of substance P on gene expression of transforming growth factor beta-1 and its receptors in rat's fibroblasts.

OBJECTIVE: To investigate the effect of substance P (SP) on gene expression of transforming growth factor beta-1 (TGFbeta-1), transforming growth factor receptor-1 (TGFR-1) and transforming growth factor receptor-2 (TGFR-2) in fibroblasts cultured in vitro from rat's granulation tissues. METHODS: The fibroblasts from the granulation tissues in the skeletal muscle of rat's hind limbs injured by formaldehyde were cultured in vitro. When different concentrations (10(-9)-10(-5) mol/L) of SP were added into the culture medium, the changes of gene expression of TGFbeta-1, TGFR-1 and TGFR-2 in the cultured fibroblasts were observed with reverse transcription polymerase chain reaction at different intervals (0, 3, 6, 12 and 24 hours after incubation). RESULTS: The gene expression of TGFbeta-1, TGFR-1 and TGFR-2 in the fibroblasts cultured from rat's granulation tissues was up-regulated by SP. The peak level of the mRNA expression was found at 10(-8) mol/L SP and the up-regulation effect was not found at 10(-5) mol/L and 10(-6) mol/L. The peak levels of gene expression of TGFbeta-1, TGFR-1 and TGFR-2 in the fibroblasts treated with SP were achieved at 6 and 12 hours, respectively. CONCLUSIONS: SP has up-regulation effect on the gene expression of TGFbeta-1, TGFR-1 and TGFR-2 in fibroblasts from rat's granulation tissues in vitro, and the effect is related to different stimulating concentrations of SP. It may be concerned with proliferation and differentiation of fibroblasts and formation of scar tissues during wound healing.

[Sensory neuropeptide SP modulating expression of EGF, FGF-2 and their receptors in fibroblasts of granulation in vivo and in vitro].

OBJECTIVE: To study the modulating effect of sensory neuropeptide substance P (SP) on gene expression of epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2) and EGF receptor (EGFR), FGF receptor-1 (FGFR-1) in granulation fibroblast. METHODS: The study consisted of two parts, in vivo and in vitro. In vivo, fifty wistar rats were randomly arranged into capsaicin group and control group. The rats in capsaicin group were subcutaneously injected with neurotoxin dose of capsaicin (50 mg/kg) on the back of the rats to chemically destroy sensory nerves to prevent the release of SP. After one week, full-thickness skin wounds were created on the rats' back. SP content and EGF, EGFR, FGF-2, FGFR-1 gene expression in the granulation tissue were observed using immunohistochemistry and in situ hybridization combined with image analysis on 3rd, 6th, 9th 12th after skin injury, respectively. The experimental procedure in control group were similar with that in capsaicin group except injection with capsaicin. In vitro, SP (10(-9)-10(-5) mol/L) was added into culture medium for cultured fibroblasts from granulation and mRNA expressions of EGF, FGF-2 and their receptors were assayed with RT-PCR. RESULTS: In the present study, immunoreactive stain for SP in granulation tissue were correlated with gene expression of EGF, FGF-2 and their receptors using in situ hybridization in vivo. Once sensory nerves were destroyed and SP release was inhibited in capsaicin group, the gene expression of above growth factors and their receptors were attenuated. SP concentrations in culture medium for upregulation of mRNA expressions of EGF and EGFR in cultured fibroblasts were from 10(-8) mol/L to 10(-6) mol/L and from 10(-6) mol/L to 10(-5) mol/L, respectively. SP concentration was from 10(-9) mol/L to 10(-5) mol/L for upregulation of FGF-2 mRNA expression in cultured fibroblasts and from 10(-6) mol/L to 10(-5) mol/L for upregulation of FGFR-1. CONCLUSION: Sensory neuropeptide SP released from sensory nerve participates in upregulation of gene expressions of EGF, EGF-2 and their receptors in granulation fibroblasts during wound healing.

[Regulative effects and significance of substance P on the expression of basic fibroblast growth factor of granulation tissue fibroblasts in vitro].

OBJECTIVE: To explore the regulative effects and significance of neuropeptide substance P (SP) on the expression of basic fibroblast growth factor (bFGF) of granulation tissue fibroblasts in vitro. METHODS: A local aseptic inflammation was induced by injection of formaldehyde in rats, and its granulation tissue was cultured. RT-PCR was employed to observe expression of bFGF mRNA after inducement of SP at different concentrations and time points in the granulation tissue, and western blot to assay expression of bFGF protein. RESULTS: The expression of bFGF mRNA was markedly increased significantly 3 and 6 hours after inducement with SP in 10(-7) mol/L, compared with control group (P < 0.01). The expression of bFGF protein was markedly higher than the control group after 12 hours, and it reached the peak at the 24th hour and declined gradually after 48 hours. SP at concentrations of 10(-9) - 10(-5) mol/L could significantly promote the expression of bFGF mRNA, and that at 10(-8) - 10(-5) mol/L induce the expression of bFGF protein. Both expressions reached the peak when SP concentration was 10(-7) mol/L (P < 0.01). CONCLUSION: SP can induce the expressions of bFGF mRNA and bFGF protein of granulation tissue fibroblasts in vitro, which may possess an important significance in wound healing.