[Role of c-Jun NH (2)-terminal kinase in insulin resistance after burn].

OBJECTIVE: To investigate the role of c-Jun NH (2)-terminal kinase (JNk) in insulin resistance after burn and its mechanism. METHODS: Twenty-four Sprague-Dawley rats were randomized to control, burn and burn + anisomycin groups. The rats in control group received sham burn trauma, and burn and burn + anisomycin groups received 30% total body surface area (TBSA) full thickness burn injury. Anisomycin (5 mg/kg) together with 250 microl dimethyl sulfoxide (DMSO) was injected to the rats in anisomycin group intravenously, and only 250 microl DMSO in the other two groups. Euglycemic-hyperinsulinemic glucose clamps was performed 2 hours after the injection. The changes of phospho-serine 307, phospho-tyrosine of insulin receptor substrate (IRS)-1 and phospho-JNK in muscle tissues were determined and compared using immunoprecipitation and Western blot analysis or immunohistochemistry in the three groups. RESULTS: The infusing rates of total 10% glucose (mg x kg(-1) x min(-1)) in control, burn and burn + anisomycin group were 12.3 +/- 0.4, 6.6 +/- 0.3, 6.5 +/- 0.4, respectively. The level of IRS-1 Serine 307 phosphorylation and phospho-JNK in muscle increased significantly, while insulin-induced tyrosine phosphorylation of IRS-1 decreased markedly after burn. CONCLUSIONS: The activation of JNK elevates the level of IRS-1 phospho-serine 307 and might play a role in insulin resistance after burn in rats.

[Experimental study of human skin fibroblasts cultured in three-dimension(3D)].

OBJECTIVE: To investigate the biological characters of human skin fibroblasts in fibroblast populated collagen lattice (FPCL). METHODS: The human fibroblasts were cultured in 3D and the collagen of the rat tail was also prepared. They were examined with the comprising cell cycle and apoptosis, mRNA expression of TGF beta1, and fibronectin, and cell morphology. RESULTS: The flow cytometry showed that the G0/G1, stage cells were 79% +/- 3%, 87% +/- 2% after the 7 days and 14 days separately, and there were not apoptosis peak observed. RT-PCR analysis revealed that the mRNA expression of TGF beta1, and fibronectin had no difference between human skin fibroblasts cultured in 3D and 2D. Electron microscope showed the cells were plenty of chromatin and organelles. CONCLUSIONS: The proliferation of the human skin fibroblasts in FPCL is slow, but its biological viability is better.

[Clinical observation of the long-term effects of rhEGF on deep partial-thickness burn wounds].

OBJECTIVE: To evaluate the safety and long-term effect of recombinant human epithelial growth factor (rhEGF) on deep partial-thickness burn wounds. METHODS: Thirty-seven burn patients were enrolled in this study and were observed by randomized, double-blinded and placebo-controlled protocol. An area of deep partial-thickness burn wounds from each patient was divided into control (C) and treatment (T) portions. The wound in C was treated with normal saline while that in T with rhEGF. The patients were followed-up for 1 and 4 years after wound healing. The healed wounds were evaluated by modified Vancouver scar scale in terms of scar index (SI). RESULTS: 1 year after wound healing, it was found that the SI in T group (7.19 +/- 1.67) was obviously lower than that in C group (8.92 +/- 1.78, P < 0.01). The SI in T group (6.12 +/- 1.54) was still evidently lower than that in C group (8.09 +/- 1.81, P < 0.01) four years after wound healing. There were no signs of development of tumor or cancer in all the tested burn wound areas. CONCLUSION: External application of rhEGF might be beneficial to the healing quality of deep partial-thickness burn wound with less scar formation and better long-term effects, and it is safe.

[Inhibition of nimodipine on production of proinflammatory by Kupffer cells in severe burned rats].

OBJECTIVE: To study whether nimodipine, a dihydropyridine-type calcium channel blocker, can inhibit the production of interleukin-1beta(IL-1beta), interleukin-6(IL-6) by Kupffer cells(KC) and down-regulate its level of plasma after severe burn injury. METHODS: KC of normal rats were isolated with portal vein catheter, intrahepatic digestion and density gradient centrifugation. Intracellular calcium concentration ([Ca2+]i) in individual KC after stimulated with postburn serum was assessed fluorometrically with microspectrofluorimeter. Level of IL-1beta and IL-6 in the supernatant of KC cultured with postburn serum were detected by enzyme-linked immunosorbent assay(ELISA). SD rats underwent 30% total body surface area(TBSA) full thickness burn 6 hours later, KCs was isolated and their mRNA were extracted. Level of IL-1beta mRNA and IL-6 mRNA were detected by ribonuclease protection assay(RPA). Levels of plasma IL-1beta and IL-6 were also detected. Role of nimodipine on above-mentioned effects were observed. RESULTS: Compared with that of control group, levels of [Ca2+]i of KCs and IL-1beta and IL-6 supernatant in burn group increased significantly(all P<0.01). At present of 1 micromol/L nimodipine, however, the [Ca2+]i, IL-1beta, IL-6 values decreased significantly(all P<0.01). The level of plasma cytokines and KC mRNA in burn group also increased significantly. After intravenously injection with nimodipine (40 microg x kg(-1) x h(-1)), the numerical values decreased significantly(all P<0.01). CONCLUSION: Kupffer cells of rats are activated to secret IL-1beta and IL-6 after severe burn injury and this process is realized through calcium ion signal transduction channel. Nimodipine can inhibit IL-1beta and IL-6 production of KC by preventing its mRNA transcription, down-regulating its level of plasma.