Search

Objective: To investigate the effect and the relevant potential mechanism of nonpeptide neurokinin 1 (NK1) receptor antagonist L-703,606 in the edema formation after burn injury., Method: L-703,606 treatment was performed in Sprague-Dawley (SD) rats at early stage after deep partial-thickness skin scalding. One hundred and fifty two adult male SD rats were used in the study and randomly divided into sham scald (SS, n=8), scald control (SC, n=48), and L-703,606 treatment (LT, n=48) groups. The rats in SC and LT groups were subjected to 20% total body surface area (TBSA) deep partial-thickness skin scalding. Modified Evans blue extravasation, tracing electron microscopy by lanthanum nitrate and mean water content assay were employed to observe and detect the changes of vascular permeability, ultrastructure and edema formation in adjacent tissue to the wounds and in the jejuna of rats at early stage (72 h) after scald., Results: The pathological increase of vascular permeability in the periwound tissue and jejunum of rats in LT group were significantly lower than that in SC group (P<0.01), and recuperated earlier. Meanwhile, the changes of water contents of corresponding tissues in LT group were lighter than those in SC group (P<0.01). The ultrastructural changes of the microvessels in the peri-wound tissue of LT group showed that the junctions between microvascular endothelium cells were more narrow than those of SC group, moreover, and the number of opening and the engorgement and cavitation of the vascular endothelium cells decreased, the areosis and edema in perivascular tissue lightened, and the precipitation of the high eletron density lanthanum tracing agent in the interspace of the tissue decreased significantly in LT group., Conclusions: It is concluded that nonpeptide NK1-receptor antagonist L-703,606 could lighten the vascular permeability and edema formation in the periwound tissue and jejunum, and accelerate the normalization process of pathological changes in the tissues of rats after scald., (Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.)

This study aimed to investigate the feasibility of using an immortal keratinocyte cell line, HaCaT cells, to effectively deliver epidermal growth factor (EGF) in a skin substitute to treat burn wounds. The skin equivalent was constructed with human EGF (hEGF) gene modified HaCaT cells obtained through stable gene transfection; these were applied to full thickness burn wounds in a rat model. The results showed that the hEGF gene modified HaCaT cells produced more than 390ng/l of bioactive hEGF in the culture supernatant. K19 and integrin-β1 as keratinocyte differentiation markers were elevated in the hEGF gene modified HaCaT cells which were shown to be non-tumorigenic. The skin equivalent constructed with hEGF gene modified HaCaT cells demonstrated improved epidermal morphogenesis with a thick and compact epidermis. Wound healing was accelerated noticeably when applied with this skin substitute seeded with hEGF gene modified HaCaT cells in vivo. The results suggest that HaCaT cells modified with hEGF gene might be promising seed cells for construction of genetically modified skin substitute which can effectively secrete hEGF to accelerate wound repair and regeneration., (Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.)

Thermal injury inhibits Akt activation and upregulates p38 mitogen-activated protein kinase, which in turn induces inflammation and increases apoptosis. This study aimed to elucidate the mechanism underlying the cytoprotective role of insulin in severe burns by examining the effects of insulin on inflammation and apoptosis mediated by p38 mitogen-activated protein kinase in burn serum-challenged cardiomyocytes. Neonatal rat cardiomyocytes were exposed to burn serum for 6 hours in the presence or absence of insulin and pretreated with inhibitors to p38 mitogen-activated protein kinase (SB203580) and Akt (LY294002). The authors examined expression of myocardial tumor necrosis factor-alpha, cardiac myofilament proteins caspase-3 and Bcl2, and apoptosis. Burn serum-induced upregulation of tumor necrosis factor was inhibited by both SB203580 and insulin. LY294002 reversed insulin-mediated downregulation of tumor necrosis factor. Both SB203580 and insulin inhibited apoptosis, resulting in fewer pyknotic nuclei and inhibition of caspase-3 activation and Bcl2 downregulation. LY294002 reversed insulin-mediated inhibition of apoptosis. Insulin decreases inflammatory cytokine expression and apoptosis via PI3K/Akt-mediated inhibition of p38 mitogen-activated protein kinase. The cytoprotective role of insulin suggests that it may have a potential role in strategies for treating thermal injuries.

Objective: To investigate the protective effect of melatonin on residual hair follicle cells of scald rats at early stage., Methods: Eighteen male Sprague-Dawley rats were randomly divided into scald group, treatment group, sham group , with 6 rats in each group. The rats in scald group and treatment group were subjected to 30% TBSA partial thickness scald on the back, and were resuscitated with balanced solution after 1 hour, while those in sham group were immersed in water at 37 degrees C for 25 s to simulate scald, and did not receive fluid replacement. Rats in treatment group were intraperitoneally injected with 10 mg/kg melatonin solution at 1 minute, 8 hours and 12 hours after scald, while those in sham group and scald group were given equal volume of 1% alcohol sodium-isotonic saline instead. Tissue samples were harvested at 6, 12 and 24 post scald hours (PSH) for determination of MDA and GSH levels. Apoptosis of residul hair follicle was detected by TUNEL method and immunohistochemistry of caspase-3., Results: The level of MDA in scald group at each time point was much higher than that in sham group (P < 0.01) and treatment group (P < 0.05), and it peaked at 12 PSH. The changes in GSH were just opposite to that of MDA. Under fluorescence microscope, the residual hair follicle cells were blue, and the apoptotic cells appeared green. The apoptosis rate in scald group at 6, 12, 24 PSH was obviously higher than that in sham (P < 0.01) and treatment groups (P < 0.05), which was (20.2 +/- 3.4)% vs (4.3 +/- 2.3)% vs (10.9 +/- 3.2)%, (31.2 +/- 3.6)% vs (5.1 +/- 2.5)% vs (19.1 +/- 3.7)%, (22.4 +/- 2.7)% vs (4.1 +/- 2.4)% vs (13.1 +/- 3.4)%, respectively. The score of caspase-3 positive cell in scald group was higher than those in sham group (P < 0.01) and treatment group (P < 0.05)., Conclusions: There is obvious correlation between oxidative stress and apoptosis rate of hair follicle cells in rats with partial thickness scald. Early administration of melatonin may have anti-apoptosis ability for residual hair follicle cells by attenuation of oxidative stress.

Objective: To investigate the protective effect of insulin on oxygen-radical induced hepatic injury in severely scalded rats in early stage of severe scald., Methods: Eighty-four male Sprague-Dawley rats were randomly divided into three groups: i. e, normal group, saline group, and insulin group, with 28 rat in each group. The rats in the latter two groups were subjected to 30% TBSA full-thickness scald on the back, and received intra-peritoneal injection of 40ml/kg isotonic saline, and subcutaneous injection of 3 IU/kg insulin, respectively. The total anti-oxygen capability (T-AOC), the expression of superoxide dismutase (SOD), reactive oxygen species (ROS) and intercellular adhesion molecule (ICAM-1) in hepatic tissue, and serum alanine transaminase (ALT) were determined in each group at 6, 12, 24, 48 post-scald hours (PSH) with corresponding methods., Results: The hepatic T-AOC and SOD content were obviously decreased, while the ROS content were markedly increased at 6 PSH in saline group compared with that in normal group (P < 0.05 or P < 0.01). The expression of ICAM-1 and serum content of ALT were significantly higher than that in normal group at 12 PSH and 48 PSH (P < 0.01). At 24 PSH, the hepatic T-AOC (386 +/- 75) U/g and SOD content (210 +/- 39 ) U/g were obviously higher in insulin group than those in saline group [(124 +/- 18), (111 +/- 9) U/g, respectively, P < 0.01), but the ROS content (154 +/- 29 ) U/g was much lower than that in saline group [(351 +/- 41) U/g, respectively, P < 0.01]. At 48 PSH, the serum content of ALT and hepatic expression of ICAM-1 in insulin group exhibited obvious difference when compared with those in saline group (P < 0.01). Meanwhile, Pathological examination showed that hepatic injury was alleviated by insulin administration after scald., Conclusion: Insulin administration early after severe scald exhibits protective effect on liver function by improving anti-oxygen radical ability of rat liver.

Objective: To investigate the protective effect of insulin on vascular endothelial cells of rats at early post-burn stage,and its mechanism., Methods: Adult male Sprague-Dawley rats were randomly divided into 3 groups: i. e, sham scald group (n = 7), scald group (n = 7) and treatment group (n = 7). The rats in the latter 2 groups were subjected to 30% TBSA full-thickness burns with 94 degrees C water, and the sham scald rats were treated with 37 degrees C water. Intra-peritoneal injection of 40 ml/kg isotonic saline solution and subcutaneous injection of 3 units/kg insulin were given to the rats in treatment group after being subjected to 30% TBSA full-thickness burns. Subcutaneous injection of equal amount of isotonic saline was given to the sham and burn groups. The changes in vascular endothelial cell structure were observed with electron microscopy at 24 post-scald hours(PSH). Meanwhile, the blood glucose contents, the serum levels of nitric oxide (NO) and nitric oxide synthetase (NOS) were determined with oxidase method and colorimetric method, respectively., Results: The injury of arterial endothelial cells in the treatment group was obviously alleviated compared with that in burn group. The blood glucose content in the treatment group (7.1 +/- 0.7 mmol/L) was significantly lower than that in scald group (8.2 +/- 1.0 mmol/L, P < 0.05), though it was much higher in both groups than that in sham scald group (4.9 +/- 0.8 mmol/L, P < 0.01) at 24 PBH. The serum content of NO, total NOS and cNOS in treatment group were obviously higher than those in scald group (P < 0.01), but there was no obvious difference in iNOS content between the two groups(P > 0.05)., Conclusion: Insulin exhibits protective effect on vascular endothelial cells in severely scalded rats at the early post-burn stage, and it is attributed to its promotion of cNOS level leading to NO production.

Objective: To study the protective effect of intensive insulin treatment on the myocardium of severely scalded rats, and to primarily explore its mechanism., Methods: Eighteen SD rats were divided into three groups, with 6 rats in each group. The rats in burn and intensive insulin group were inflicted with 30% TBSA full-thickness injury on the back. Isotonic saline containing 0.12 U/ml insulin solution, and 100 g/L glucose solution were infused into the rats in the intensive insulin group to keep plasma glucose at the level of 4.0 - 6.6 mmol/L (the total fluid amount was 2 ml x kg(-1) x 8h(-1)). In sham burn group,fluid was given according to physiological demand. The same amount of isotonic saline was infused into the rats in burn group. The venous blood was obtained for the detection of plasma glucose contents, and the left ventricular systolic pressure (LVSP) and left ventricular end-diastolic pressure (LVEDP) were recorded via aortic ventricle cannula before scald and at 1, 2, 3, 4, 5, 6 post-scald hours (PSH). The tissue of the left ventricle was harvested at 6 PSH for the detection of troponin T expression in myocardiocytes., Results: Plasma glucose level was increased to (7.6 +/- 1.7) mmol/L - (8.4 +/- 4.7) mmol/L in burn group during 1-6 PSH, which was significantly higher than that in intensive insulin group (4.5 +/- 0.9) mmol/L - (5.2 +/- 1.3) mmol/L, P < 0.01). Compared with the intensive insulin group, LVSP was markedly decreased in the burn group (60 +/- 11 mm Hg vs 72 +/- 8 mm Hg, P < 0.05) at 1 PSH,whereas LVEDP was increased significantly (21.3 +/- 11.3 mmHg vs 11.7 +/- 5.2 mmHg, P < 0.05). Intensive insulin treatment could significantly inhibit the loss of troponin T protein in myofilaments of myocardium., Conclusion: Intensive insulin treatment possesses a protective effect on myocardia function after severe burns, and it may be related to its preventive effect on the loss of contractile protein in cardiocytes.

Objective: To establish a rat model of scalding with controllable depth and area by high pressure steam., Methods: High pressure steam apparatus consisting of an autoclave and a self-made scalding frame was employed in the study. The rats were inflicted with scalding with 0.12 Mpa (1 Mpa = 7500 mmHg) high pressure steam on the back through a hole of 2.6 cm in diameter for 3, 4, 5, 6, 7, 8, 9 and 10 seconds, with five wounds at each time point. The tissue samples were harvested at 24 post injury hour (PIH) for pathomorphological examination. The depth of scald was measured, and injury to the sweat gland and hair follicles injury, the hair growth in scalded area, and the wound healing condition were observed with Photoshop software., Results: There was positive correlation between the scalding depth and scalding time. The injury time for superficial and deep partial thickness burn and full thickness burn were 3, 5 and 7 seconds respectively. The wound healing time was similar even the scalding became more and more serious when injury time increased from 7 to 10 seconds., Conclusion: The scalding depth and area in this model could be controlled, and the degree of scald injury could be graded accurately with easy manipulation. The result showed that it was an ideal model of skin burn wound.

Objective: To investigate the change in neuropeptide substance P (SP) in the burn wound skin in scalded rats., Methods: The SP distribution density in the rat skin samples from the burn wound, peri-wound area and remote area of scalded rats were determined by immunohistochemistry technique. The mRNA expression of SP was observed by in situ hybridization., Results: The distribution density of SP in the skin samples from the above three areas decreased obviously since 15 mins postburn, dropped to the lowest level during 6 - 12 postburn hou (PBH), and then recovered thereafter. Comparatively, the recovery in peri-wound area occurred earlier. In addition, there was emigration of macrophage-like large cells with positive SP immunoreactivity from local blood vessels in the dermal layer of the burn wound and peri-wound areas. The large cells were closely related to the local SP-containing nerve fibres at 12 PBHs. Intensified staining of the cells was identified at 24 PBHs with the disintegration of the cells into pieces with release of large amounts of positive SP immunoreactive granules, followed by disappearance of the cells at 48 PBHs. It was indicated by in situ hybridization that the preprotachykinin A (PPTA) mRNA encoding and synthesizing SP was expressed in various cells at 6 PBHs., Conclusion: SP might be synthesized and released from cutaneous nerve ending or from local inflammatory cells after skin burn injury.

Objective: To establish a long-term in vitro culture of the fibroblasts obtained from burn wounds., Methods: Skin samples were harvested from normal volunteers and the deep partial thickness burn wound in burn patients on the 5th, 10th, 21st, 28th and 35th postburn days (PBDs). The non-dermal tissue was removed from the samples and primed by chlorhexidine solution in concentration of 2.5 g/L. The skin sample was then digested by trypsin-EDTA in concentration of 1.25 g/L and was centrifuged before the cells were harvested and cultured. When the cells grew nearly to form sheet, multiple passage culture, freezing storage and revivification were carried out with routine methods. The cell morphology was continuously observed during the culture. And the cell doubling time was calculated., Results: The wound-origin fibroblasts exhibited higher purity and better activity. The cellular growth features and gross morphology kept stable during primary and secondary culture, and during freezing storage and after revivification. The cells kept their activity above 80% of their original after many times of revivification., Conclusion: The establishment of the in vitro culture of fibroblasts from burn wounds might be useful in the exploration of the pathogenesis and therapeutic measures of scars.