Effects of advanced glycosylation end products on the biological behavior of neutrophils / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effects of advanced glycation end products (AGE) on the biological behavior of neutrophils in vitro, to look for the relationship between accumulation of AGE and abnormal inflammation in wound healing in diabetic mellitus patients.</p><p><b>METHODS</b>Neutrophils were isolated from SD rats and incubated in vitro. The cells were divided into four groups according to different concentrations of AGE in cell suspension: control group (C, with treatment of RPMI - 1640), A group (with treatment of 0.315 mg/mL AGE + RPMI - 1640), B group (with treatment of 0.625 mg/mL AGE + RPMI - 1640), D group (with treatment of 1.250 mg/mL AGE + RPMI - 1640). Activity of neutrophils were determined by MTT colorimetric assay. Selectin-L mRNA expressions were analyzed by reversible transcription polymerase chain reaction (RT -PCR) technique. The levels of reactive oxygen species (ROS) in neutrophils were measured with DCFH-DA method. The protein concentration of neutrophil elastase (NE) was assayed by ELISA.</p><p><b>RESULTS</b>The activity of neutrophils were obviously increased in A, B, and D groups when compared with that in C group [(0.170 +/- 0.040) in C group, (0.320 +/- 0.030) in A group, (0.380 +/- 0.020) in B group, (0.290 +/- 0.010) in D group, P <0. 05]. The expression of Selectin-L mRNA in A, B, D groups were significantly higher than that in C group (0.95 +/- 0.08, 1.36 +/- 0.27, 0.50 +/- 0.26.vs.0.36 +/- 0.26, P < 0.05. respectively). The ROS levels in A, B, D groups was markedly higher than that in C group (1.64 +/- 0.20, 2.16 +/- 0.26, 3.26 +/- 0.75. vs. 0.72 +/- 0.15, P <0.05, respectively). The levels of NE in A, B, D groups were significantly increased when compared with that in C group(1.98 +/- 0.43, 2.50 +/- 0.43, 2.01 +/- 0.18 vs 0.91 +/- 0. 21, P <0.05, respectively).</p><p><b>CONCLUSION</b>AGE can enhance the activity of neutrophil, with change in cellular biological behaviors, which may be one of main reasons for abnormal inflammation in wounds of diabetes mellitus patients.</p>

Study of neovascularization disturbance in deep partial-thickness scald in rats with diabetes mellitus / 中华烧伤杂志

<p><b>OBJECTIVE</b>To study the relationship between the degree of neovascularization and non-healing wounds in scalded rats with diabetic mellitus.</p><p><b>METHODS</b>Sixty Sprague-Dawley rats were randomly divided into control group (C, n = 30, with treatment of isotonic saline) and streptozocin (STZ)-induced diabetic group (D, n = 30, with treatment of STZ), and then they were inflicted with 20% TBSA deep partial thickness scald. Wound specimens were harvested immediately after scald and on 1, 3, 7, 10, 14, 21 post scald days (PSD) to observe histological changes, and wound healing rates were calculated. Degree of neovascularization in wound (labeled with blue microsphere) and the quantity of vascular endothelial cells (labeled with red CD31) were also measured by double-labeling immunofluorescence.</p><p><b>RESULTS</b>Compared with those in C group, Wound healing rate and histological value scores were lowered, and the degree of neovascularization was abated markedly at each time point. The degree of neovascularization in D group (12.00 +/- 1.40) was obviously lower than that in C group on 7 PSD (60.00 +/- 3.00, P <0.01). There was no obvious difference in the number of vascular endothelial cells in both groups, however, the majority of endothelial cells had not formed functional capillaries in D group.</p><p><b>CONCLUSION</b>Vascular endothelial cell can proliferate actively with poor blood supply in diabetic nonhealing with deep partial-thickness scald wounds, but it is still poor in blood supply due to lack of functional capillaries.</p>

Study on the mechanism of scar formation: epidermis template defect theory / 中华烧伤杂志

Dermal defection and the degree of its loss determine the natural process of wound healing, which is the key reason leading to excess scar hyperplasia. The function of tri-dimensional structure in dermis acts as a template to regulate the properties of reparative cells. The template structure induces the reparative cells to grow into the structure which changes the skin mechanic status on wound area. Also, the component of extracellular matrix can affect behaviours of fibroblasts negatively or positively, for the reason that the structure of dermal tissue has a permissive effect on the dermal components in regulating behaviours of reparative cells. Therefore, the behaviors of cells depend on the structure of the template. The suitable tri-dimensional structure of dermis facilitates normal cell cycling. The more the structure of dermis closed to its physiological status, the better the biological behaviors of cells act. Moreover, the integrity as well as the continuity of dermal tissue is the prerequisite for serving as a template. The damage to the integrity and the continuity of dermal tissue may be one of the key reasons to lead abnormal tissue repair and scar formation. Thus, we hypothesize that the loss of dermal template may be one of the mechanism of abnormal scar formation and propose the theory of extracellular matrix framework deficiency or destruction.

Influence of tangential excision within 24 postburn hours on the local wound inflammatory response in patients with deep partial thickness burn / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of early tangential excision within 24 postburn hours on local wound inflammatory response and tissue injury in patients with deep partial thickness burn.</p><p><b>METHODS</b>Twelve patients with deep partial thickness burn were enrolled in the study. Tangential excision was performed within 24 postburn hours. The same wound of a patient was divided into three areas for harvesting tissue samples, i.e. pre-operation, post-operation and non-operation areas. For each patient, the biopsies from the pre-operation area were harvested before tangential excision, while those from post-operation and non-operation areas were harvested during 5 to 7 postburn days (PBDs). The contents of IL-8, MPO and MDA in wound tissue were determined by tissue culture and chemical colorimetry, respectively. HE and Mason's staining were employed to assess the degree of necrosis of the wound tissue.</p><p><b>RESULTS</b>The IL-8, MPO and MDA contents in the local wound tissue after tangential excision were 6.83 +/- 1.85 microg/L, 4.07 +/- 0.87 U/g, and 8.94 +/- 5.66 micromol/g, respectively, which were significantly lower than those from non-operation area (P < 0.01). The inflammatory response in the non-operative wound area was distinct with expansion of necrotic tissue area. In contrast, the local inflammatory response of the wound after tangential excision was ameliorated without the enlargement of necrotic tissue area.</p><p><b>CONCLUSION</b>Tangential excision within 24 postburn hours could be beneficial in ameliorating local inflammatory response, and in preventing progressive deepening of the burn wounds, thus it could accelerate wound healing in patients with deep partial thickness burn.</p>

Influence of L-arginine supplementation on the plasma amino acid spectrum in burn patients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the influence of L-arginine supplementation on the plasma amino acid spectrum in burn patients.</p><p><b>METHODS</b>Ten burn patients were randomly divided into burn control (n = 5, with compound 14 amino acid injection accounting for 2% of the total caloric value), and experimental (n = 5, with intravenous injection of L-arginine which accounted for 2% of total caloric value) groups. The intake of other nutrients for these two groups of patients was the same. The nutrient regimen was begun on the 3 PBD, with one quarter of the daily supply. On 4 and 5 PBD, one half of the daily supply was given, and from 6 to 21 PBD full supplementation was given. Venous blood samples were collected on 3, 7, 14, 21 and 28 PBD for the determination of plasma levels of amino acids. Ten normal volunteers served as normal control.</p><p><b>RESULTS</b>The plasma level of citrulline in both groups was significantly lower than normal value (P < 0.05) on 3 PBD before L-arginine supplementation. There was no obvious difference in plasma levels of ornithine and arginine in the two groups on 3 PBD compared with normal value (P > 0.05). The plasma level of ornithine, citrulline and arginine in burn control group declined on 3 PBD. The plasma level of arginine in experimental group on 14, 21 and 28 PBD were 280 +/- 121 micromol/L, 223 +/- 106 micromol/L and 110 +/- 44 micromol/L, respectively, which were significantly higher than those in burn control group (124 +/- 21 micromol/L, 59 +/- 15 micromol/L, 50 +/- 26 micromol/L). The plasma level of ornithine (30 +/- 5 micromol/L) and citrulline (162 +/- 44 micromol/L) on 21 PBD in experimental group were markedly higher than those in burn control group (8 +/- 7 micromol/L, 66 +/- 4 micromol/L, P < 0.05 or 0.01). There was no difference in the plasma levels of other amino acids at all postburn time points between the two groups (P > 0.05).</p><p><b>CONCLUSION</b>The production process of L-arginine from citrulline was accelerated after burns. The plasma levels of L-arginine, ornithine and citrulline were increased markedly after L-arginine supplementation, while that of other amino acids was not influenced. The pharmacological effects of L-arginine may be related to the promotion of ornithine cycle.</p>

Establishment of an animal model with hypertrophic scar / 中华烧伤杂志

<p><b>OBJECTIVE</b>To establish an animal model of hypertrophic scar on the rabbit ears and to observe the dynamic process of scar formation on the ventral side of the rabbit ears.</p><p><b>METHODS</b>Full skin defect (2 cm x 5 cm in diameter) was created on the ventral side of 60 ears in 32 New Zealand white rabbits. 1% silver sulfadiazine cream was applied to the wounds, and the dressing was changed once a week till wound healing. Four ears without operation were taken as control. Wound healing under natural condition was observed continuously for 12 months after the operation. The scar proliferation on the rabbit ears was observed by light microscope and transmission electron microscope, and the scar index was determined by computer image analyzing system.</p><p><b>RESULTS</b>The color, thickness and texture of the wounds on the rabbit ears after epithelization underwent a process of scar overgrowth, maturation and degeneration. The change in scar index was in accordance with the wax and wane of scar proliferation.</p><p><b>CONCLUSION</b>The hypertrophic scar formed on the ventral side of rabbit ears after natural healing of full thickness skin wounds was similar to that in humans. The results indicated that this animal model was ideal for the study of the developmental mechanism of hypertrophic scars and for the evaluation of the efficacy of the prevention and treatment of hypertrophic scars.</p>

An experimental study on the effects of postburn dietary supplementation of enhanced nutrients / 中华烧伤杂志

<p><b>OBJECTIVE</b>To evaluate the effects of postburn dietary supplementation of arginine (Arg), omega-3 polyunsaturated fatty acid (omega-3PUFA) and glutamine (Glu) on the metabolism, immunology and wound healing in scalded rats.</p><p><b>METHODS</b>Thirty Sprague-Dawley (SD) rats inflicted with 30% total body surface area deep partial thickness scald on the back after the gastrostomy catheter was placed were employed as the model. The rats were randomly divided into A and B groups, and all of them received continuous isonitrogenous (25% protein, 12% fat, 63% carbohydrate), isocaloric (175 kcal/kg/day), and isovolemic intragastric tube feedings. The contents of Arg, omega-3PUFA, Glu in the dietary of B group were enriched. The parameters were measured on the 10th day after injury, including the response of spleen cells to ConA, the plasma levels of PGE(2), IL-2, albumin, transferrin, glucagons, cortisol in blood, the urinary content of vanillylmandelic acid (VAM) in 24-hour urine, the content of hydroxyproline, the ratio of type I to type III collagen in burn wounds, and the nitrogen content in the liver and in the jejunal mucosa, as well as the weight changes, skin delayed hypersensitivity test, and wound healing time.</p><p><b>RESULTS</b>It was revealed that the serum level of albumin, the nitrogen content in the liver and in the jejunal mucosa were obviously higher in B than those in A group. At the same time, there was no statistical difference in the plasma levels of cortisol and glucagons and urinary content of VAM between the two groups, nor in body weight changes. Meanwhile, the response of spleen cells to ConA and the skin delayed hypersensitivity induced by DNFB 14 days after injury in group B were also enhanced compared with those in group A. Although the expression of PGE2 from peritoneal macrophages was lower, the content of hydroxyproline from burn wounds in group B was significantly higher than that in group A, and the ratio of type l to type III collagen in group B was significantly lower than that in group A. Compared with group A, the wound healing time in group B was significantly shortened (P < 0.05).</p><p><b>CONCLUSION</b>The low-fat and high-protein feeding diet with enriched arginine, omega-3 PUFA, glutamine could benefit the nutritional status after burn injury, thus improve the immunological function and promote wound healing.</p>

Effects of advanced glycation end-products on skin keratinocytes by NF-?B activation / 中华创伤杂志

Objective To investigate the effects of advanced glycation end-products(AGEPs)on the function of normal keratinocytes in vitro so as to explore the role of AGEPs in impaired wound healing. Methods Normal rat keratinocytes were incubated with different concentrations of AGEPs.After 48 hours of culturing,the cell proliferation rates were measured by MTT colorimetric determination.The cell cycle distributions and apoptosis were analyzed with flow cytometry,and the migration was investigated by 24-well fluorimetric cell migration assay kit by exposing to 100?g/ml AGEPs.Nuclear extracts from these cells were examined for binding of nucleotides containing NF-?B consensus by immunocytochemistry and EMSA in vitro.Results The proliferations of normal keratinocytes were significantly arrested and many cells were induced to early apoptosis compared with control ones(P＜0.05)by exposing to AGEPs for 48 hours. Meanwhile AGEPs also irritated keratinocytes migration compared with control ones(P＜0.05).Inhibiting the activation of NF-?B could partly recover the proliferation of keratinocytes,reverse apoptosis and attenu- ate migration.Conclusion AGEPs are correlated with the migration,proliferation and apoptosis of kera- tinocytes by NF-?B.