Experimental research on the management of combined radiation-burn injury in China.

Combined radiation-burn injury can occur in people exposed to nuclear explosions, nuclear accidents or radiological terrorist attacks. Using different combined radiation-burn injury animal models, the pathological mechanisms underlying combined radiation-burn injury and effective medical countermeasures have been explored for several years in China, mainly at our institute. Targeting key features of combined radiation-burn injury, several countermeasures have been developed. Fluid transfusion and the calcium antagonist verapamil can prevent early shock and improve myocardial function after combined radiation-burn injury. Recombinant human interleukin 4 (rhIL-4) is able to effectively reduce bacterial infection and increase intestinal immunological ability. Chitosan-wrapped human defensin 5 (HD5) and glucagon-like peptide 2 (GLP-2) nanoparticles can increase the average survival time of animals with severe combined radiation-burn injury. After treatment by cervical sympathetic ganglia block (SB), hematopoietic function is promoted and the release of inflammatory cytokines is suppressed. The optimal time for escharectomy and allo-skin grafting is 24 h after injury. Transfusion of irradiated (20 Gy) or stored (4°C, 7 days) blood improves the survival of allo-skin grafting and allo-bone marrow cells. In conclusion, as our understanding of the mechanisms of combined radiation-burn injury has progressed, new countermeasures have been developed for its treatment. Because of the complexity of its pathology and the difficulty in clinical management, further efforts are needed to improve the treatment of this kind of injury.

Protective effect of atorvastatin on radiation-induced vascular endothelial cell injury in vitro.

Vascular endothelial cells are very sensitive to ionizing radiation, and it is important to develop effective prevent agents and measures in radiation exposure protection. In the present study, the protective effects of atorvastatin on irradiated human umbilical vein endothelial cells (HUVEC) and the possible mechanisms were explored. Cultured HUVEC were treated by atorvastatin at a final concentration of 10 µ mol/ml for 10 minutes, and then irradiated at a dose of 2 Gy or 25 Gy. Twenty-four hours after irradiation, apoptosis of HUVEC was monitored by flow cytometry, and the expression of thrombomodulin (TM) and protein C activation in HUVEC was respectively assessed by flow cytometry and spectrophotometry. After treatment with atorvastatin for 24 h, the rate of cell apoptosis decreased by 6% and 16% in cells irradiated with 2 Gy and 25 Gy, respectively. TM expression increased by 77%, 59%, and 61% in untreated cells, 2 Gy irradiation-treated cells, and 25 Gy irradiation-treated cells, respectively. The protein C levels in 2 Gy and 25 Gy irradiation-treated cells were reduced by 23% and 34% when compared with untreated cells, but up-regulated by 79% and 76% when compared with cells which were irradiated and treated with atorvastatin. In conclusion, these data indicate that atorvastatin exerts protective effects on irradiated HUVEC by reducing apoptosis by up-regulating TM expression and enhancing protein C activation in irradiated HUVEC.

Effects of serum from rats with combined radiation-burn injury on the growth of hematopoietic progenitor cells.

BACKGROUND: This study aims to observe the effects of blood serum from rats with radiation injury, burn injury, and combined radiation-burn injury on the growth of hematopoietic progenitor cells and to explore the possible mechanisms. METHODS: Serum from rats with radiation injury, burn injury, and combined radiation-burn injury were collected at 3 hours, 12 hours, 24 hours, 48 hours, 72 hours, and 96 hours after injury and then was added to the culture medium to see its effect on the growth of hematopoietic progenitor cells (HPCs) at a final protein concentration of 10 microg/mL. Radioimmunoassay and enzyme-linked immunosorbent assay were employed to measure the level of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in each group, and the effect of TNF-alpha and IL-6 on the growth of HPC was also observed. RESULTS: The number of HPCs colonies formed after addition of the serum from rats with burn or combined radiation-burn injuries was significantly higher than that from normal rats at 3 hours, 12 hours, 24 hours, 48 hours, 72 hours, and 96 hours after injury and reached its peak value at 24 hours after injury. However, fewer HPCs colonies were found after the addition of the serum from irradiated rats. At the same time, the levels of TNF-alpha and IL-6 in the serum of burn group and combined radiation-burn injury group were significantly higher than that of normal group, and much higher than that of the irradiation injury group (p < 0.01). Also, TNF-alpha and IL-6 demonstrated promoting effect on the growth of HPC. CONCLUSION: Serum from rats with burn injury and combined radiation-burn injury stimulates the growth of HPCs, while serum from irradiated rats shows inhibitory effects on the growth of HPCs. These effects may lie in the different level of TNF-alpha and IL-6 in the serum of each group.

[Effects of blood serum from rats with combined radiation-thermal injury on the bone marrow hematopoietic progenitor cells growth].

To observe the effects of blood serum from rats with radiation injury, thermal injury and combined radiation-thermal lesions on growth of hematopoietic progenitor cells and the change of their serum cytokine levels, total body irradiation of rats was performed with 12 Gy gamma ray from a (60)Co source, and 30% total body surface area III degree thermal lesion on the back was inflicted with a 5 kW bromotungsten lamp. The blood serum from these animals was collected at 3, 12, 24, 48, 72 and 96 hours after injury. Then the blood serum was added to the culture medium of erythrocyte progenitor cells (CFU-E, BFU-E) or granulocyte-macrophage progenitor cells (CFU-GM) at final concentration of 10 microg/ml. The results showed that the colony number of CFU-E, BFU-E and CFU-GM formed after addition of the blood serum from rats with thermal or combined radiation-thermal injury was significantly higher than that from normal rats at 3, 12, 24, 48, 72 and 96 hours after injury and reached its peak value at 24 hours after injury (342.8, 261.6 and 228.4% respectively from burned rats, 252.4, 205.1 and 174.2% respectively from rats with combined radiation-thermal injury as compared with that of normal rats). However, a few CFU-E, BFU-E or CFU-GM formation was found after addition of the blood serum from irradiated rats. At the same time, the level of TNF alpha and IL-6 in serum of burn group and combined radiation-thermal injury group was markedly higher than that of normal group, even more higher than that of irradiation injury group (P < 0.01). It is concluded that the blood serum from rats with thermal lesion or combined radiation-thermal injury improves the growth of erythrocyte and granulocyte progenitor cells. On the contrary, the blood serum from the irradiated rats shows the inhibiting effects, definitely related to their serum cytokines changes.