Influence of hyaluronic acid on wound healing using composite porcine acellular dermal matrix grafts and autologous skin in rabbits.

This study aims to explore the influence of hyaluronic acid (HA) on wound healing during xenogeneic porcine acellular dermal matrix (PADM) composite skin grafting. The results will facilitate the development of methods for improving graft contracture and poor elasticity of composite transplantation. Exogenous HA was added to composite PADM grafts and to thin autologous skin grafts during rabbit full-thickness skin wound repair. The influence of HA on wound healing was evaluated according to its contracture rate and its expression of collagen types I and III. The possible mechanism was then explored based on HA metabolism and vascularisation in the skin graft. The results show that exogenous HA relieves graft contracture on rabbit wound surfaces, increases collagen I and III expression and decreases the ratio between collagen types. HA stimulates the generation of more CD44 receptors to strengthen its enzymolysis. The resulting metabolites promote the vascularisation of the wound surface, which are conducive for mitigating graft contracture, and further improve the composite grafting effect.

[Voltage dependent anion channel 2 involved mitochondrial apoptosis and its possible regulatory signal pathway in hearts of rats with severe scalds].

OBJECTIVE: To explore the role of voltage dependent anion channel 2 (VDAC2) involved mitochondrial apoptosis in heart injury of rats with severe scald injury and elucidate its possible regulatory signal pathway. METHODS: A total of 60 Wistar rats were divided into sham scald group (n = 30) and scald group (n = 30) according to a random digital table. Blood and heart tissue samples were harvested at Day 1, 7, 14 post scalding. Myocardial injury was assessed with cardiac troponin I (cTnI) by enzyme-linked immunosorbent assay (ELISA). Mitochondrial apoptosis activation was evaluated by the expressions of Bax/Bcl-2 ratio, cytoplasmic cytochrome C and VDAC2. And the levels of phosphatidylinositol 3-kinase, p-Glycogen Synthase Kinase-3ß and hexokinase 2 protein were determined by Western blot. RESULTS: The serum levels of cTnI were significantly higher in scald group than those in sham scald group at Day 1, 7, 14 ((1.41 ± 0.25) vs (0.53 ± 0.23) µg/L, (1.93 ± 0.53) vs (0.43 ± 0.23) µg/L, (1.62 ± 0.34) vs (0.41 ± 0.22) µg/L respectively, all P < 0.05). Compared with sham scald group, Bax/Bcl-2 ratio increased significantly in scald group at Day 1, 7 day post-scalding (3.360 ± 0.173 vs 0.623 ± 0.044, 2.736 ± 0.341 vs 0.698 ± 0.064, 1.290 ± 0.234 vs 0.718 ± 0.063 respectively, all P < 0.05), VDAC2 protein level in scald group decreased significantly at Day 1, 7, 14 (0.070 ± 0.009 vs 0.328 ± 0.026, 0.007 ± 0.002 vs 0.291 ± 0.025, 0.009 ± 0.004 vs 0.302 ± 0.037 respectively, all P < 0.05), the cytoplasmic levels of cytochrome increased significantly in scald group at Day 1, 7, 14 (0.418 ± 0.030 vs 0.022 ± 0.007, 1.685 ± 0.169 vs 0.030 ± 0.011, 0.300 ± 0.037 vs 0.098 ± 0.014 respectively, all P < 0.05), the expression of PI3K was significantly lower in scald group at Day 14 post-scalding (0.083 ± 0.015 vs 0.328 ± 0.011, P < 0.05), the expressions of p-GSK3ß all reduced significantly at Day 1, 7, 14 (0.098 ± 0.014 vs 0.446 ± 0.031, 0.064 ± 0.002 vs 0.476 ± 0.054, 0.074 ± 0.010 vs 0.442 ± 0.041, respectively, all P < 0.05) and the expressions of HK2 were lower at Day 7, 14 post-scalding (0.390 ± 0.027 vs 0.611 ± 0.070, 0.267 ± 0.018 vs 0.490 ± 0.042, respectively, all P < 0.05). CONCLUSIONS: VDAC2 involved mitochondrial apoptosis is activated in myocardium after severe scalds. And it may be regulated by the pathway of PI3K-GSK-HK2.

[Functions of exogenous application of connective tissue growth factor in stimulating human dermal papilla cells and human hair follicle outer root sheath cells for reconstructive tissue-engineering hair follicles].

OBJECTIVE: To explore the functions of connective tissue growth factor (CTGF) in the restoration of hair follicles with a mixture of human dermal papilla cells and human hair follicle outer root sheath cells in vitro in nude mice. METHODS: Human hair follicle outer root sheath cells (hfORS) and human hair dermal papilla cells (hDP) were cultured in vitro and mixed in a fixed ratio (hfORS: hDP = 5:1). Flow cytometry was used to detect the content of CD200(+) cells in human hair follicle outer root sheath cells.And 8 nude mice were divided randomly into 2 groups according to a random number table and back wounds produced. Group A was transplanted with cell mixture plus 20 µg/L CTGF. Group B was transplanted with cell mixture alone. After 8 weeks of transplantation, the development of hair follicle formation was observed histologically.PCR was used to detect the expression of human specific DNA and mice DNA in transplants. RESULTS: The portion of CD200(+) cells in cultured hfORS was 19.65%. At 8 weeks after implantation, hair follicle formation could be observed in Group A (268 ± 96) more than Group B (62 ± 20). The difference was statistically significant (P < 0.05). And PCR showed that there was human composition in transplant. CONCLUSION: CTGF can induce the formation of hair follicle by promoting the interference between hDP and hfORS.

[Clinical study of repairing donor site of thickness from cicatricial skin with auto-scalp grafting].

OBJECTIVE: To study the effects of using auto-scalp for repairing donor site of thickness from cicatricial skin with auto-scalp grafting. METHODS: A total of 13 cases with donor site of thickness from cicatricial skin from January 2011 to December 2011 were analyzed. Wounds of donor site from cicatricial skin were grafted with auto-scalp and scalp were fixation was applied with negative pressure. The survival rate of auto-scalp graft was observed at Day 7 post-operation. At Month 12, hyperplastic scars at these donor sites of cicatricial skin were assessed through Vancouver Scar Assessment Table, scar itch assessment and scar proliferation rate. Wounds in the other thirteen cases with donor site of thickness from cicatricial skin from January 2010 to December 2010 were covered with vaseline gauze as control. RESULTS: No significant difference existed in the gender and age of the two groups patients (P > 0.05). The auto-scalp graft all survived. And the average healing time of donor-site wound in cicatricial skin in grafting group (7 days) was significantly decreased than that of control group (a mean of 20 days) (P < 0.01). After followed up for twelve months, the scar formation assessment value (1.5 ± 0.5), scar itch assessment (1.2 ± 0.4) and scar proliferation rate (14.6% ± 7.6%) in grafting group were significantly less than those of control group (6.7 ± 1.1, 2.0 ± 0.7, 55.8% ± 12.2%, all P < 0.01). CONCLUSION: Auto-scalp grafting may greatly shorten the healing procedure and ameliorate the quality of donor-site of thickness from cicatricial skin.

[Comparison of different methods for the isolation of human umbilical cord mesenchymal stem cells].

OBJECTIVE: To explore the most appropriate method for the isolation of human umbilical cord mesenchymal stem cells (MSCs) through a comparison of different methods. METHODS: Fifteen umbilical cord specimens from full-term healthy fetus with caesarean birth were completely rinsed with phosphate buffer saline (PBS) and sliced into 1 mm(3) tissue blocks after removal of umbilical vessels and external membrane. These tissue blocks were averagely divided into 4 groups after washing and centrifuge. Then four methods for the isolation of human umbilical cord MSCs were compared: an explant culture and three enzymatic methods of collagenaseII, collagenaseII/trypsin and collagenaseII/hyaluronidase. The count of living cells was evaluated by trypan blue dye exclusion test. Cell morphology was observed under inverted microscope. The expressions of cell surface markers CD105, CD90, CD73, CD31, CD44, CD45, human leukocyte antigen-I (HLA-I) and human leukocyte antigen class IImolecules (HLA-DR) were detected by immunofluorescent staining. Cell proliferation was assayed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). RESULTS: The human umbilical cord MSCs were successfully isolated by four isolated methods. However the isolation method used profoundly altered the cell number and proliferation capacity of isolated cells. Isolated cells using four methods were counted at (5.44 ± 0.21)×10(5), (4.03 ± 0.24)×10(5), (4.91 ± 0.33)×10(5) and (5.94 ± 0.40)×10(5) respectively. More cells were obtained with collagenaseII/hyaluronidase than other three methods (all P < 0.05). Cells out of tissue blocks were observed at Day 9-11 and cells were observed at Day 2 with three types of enzyme digestion. The fusion time of cells were (18.5 ± 3.5), (8.0 ± 1.0), (7.5 ± 1.5) and (3.5 ± 0.5) days respectively. The fusion time of cells obtained with collagenaseII/hyaluronidase was lower than other methods (all P < 0.05). Cell morphology: polygonal, irregular and of large volume for explant culture; relatively short and small for collagenaseII and collagenaseII/trypsin methods; thin spindle for collagenaseII/hyaluronidase method. Immunofluorescent staining revealed that CD105, CD73, CD90 and CD44 were expressed in all groups while there was no expression of CD31, CD45 or HLA-DR. And the cells obtained with collagenaseII/hyaluronidase method were in a higher cell proliferation rate and activity compared to other methods. CONCLUSION: The collagenaseII/hyaluronidase method is optimal for the isolation of human umbilical cord MSCs than other methods.

[Effects of hyaluronic acid on biomechanic performance of porcine acellular dermal matrix plus thin skin autograft after transplantation].

OBJECTIVE: To explore the effects of hyaluronic acid (HA) on biomechanical properties for porcine acellular dermal matrix (PADM) plus thin skin autograft after transplantation. METHODS: The dorsa of 10 Japanese white rabbits were symmetrically divided into four areas of A-D by random grouping. Full-thickness skin defects were created in Groups A-C while Group D was blank with normal skin. Operations were performed in Group A: implant with HA + PADM + thin skin autografts, Group B: implant with PADM + thin skin autografts and Group C: skin autografts group. Histological examination of specimen was performed at Day 56 postoperatively. And the biomechanical properties such as relaxation and stress-strain properties of grafts were recorded. RESULTS: The structure of PADM was found to be basically intact by hematoxylin and eosin E dyeing in Groups A and B. In Group A, dense fiber structure could be observed. Lots of regularly arranged collagenous fibers and new blood capillaries were grown into the dermal matrix with sparsely distributed inflammatory cells. In Group B, acellular dermal matrix became clustered with a small amount of invaded fibroblasts. And there was a high expression of inflammatory cells. The biomechanic performances of transplanted skin were: Group A's curve was mostly close to that of Group D's, Group B's curve was the most further from that of Group D's (P = 0.001) and Group C's curve stayed between Groups A and B. Under the same strain, the stress of Groups A-D was (87 ± 8), (115 ± 9), (63 ± 7) and (81 ± 4) kPa respectively. No significant difference of stress existed between these two groups (P = 0.838). There was significant difference of stress between Groups B/C and D (P = 0.001 and P = 0.009). CONCLUSION: Topical hyaluronic acid may be used to enhance the biomechanics performances of transplanted skin.

[Experimental study of hyaluronic acid on the biomechanical compliance of porcine acellular dermal transplantation].

OBJECTIVE: To explore the effect on biomechanical compliance after an addition of hyaluronic acid (HA) in transplantation of porcine acellular dermal matrix (PADM) with skin autograft. METHODS: Ten Japanese white rabbits were used as experimental animal, the dorsa of rabbits was symmetrically divided into four area, and then grouping was randomized. Full-thickness skin defects were created in Group A to Group C, and Group D was blank group with normal skin. The following procedures were performed: Group A: implanted with HA+PADM+ thin skin autografts, GroupB: implanted with PADM+ thin skin autografts and Group C: skin autografts, except for Group D. The wound tissue specimens were harvested at 70 days postoperatively, and they were recorded contracture rates of the grafts and the biomechanical compliance by Instron biomechanics tensiometer. The expression of collagens I and III in dermal fibroblasts of each group was determined by Western blot. RESULTS: On postoperation day 70, the grafts contracture rates in Group A to Group C were 10.2% ± 0.6%, 36.6% ± 0.8%, 32.7% ± 1.4% respectively, there were notable significant difference among three groups (P = 0.000). Under the same tension, there was no significant difference in strain between Groups A and D ((83 ± 8) vs (81 ± 5) kPa, P = 0.552). Some significant difference in strain existed between Groups B and D ((215 ± 9) vs (81 ± 5) kPa, P = 0.000). The strain of Group C ((106 ± 7) kPa) was between Groups B and D, and significant strain difference existed among them (P = 0.000). The expressions of collagens I and III in Group A were higher than those in Group B, while the ratio of collagens I to III in Group A was lower than that in Group B. CONCLUSION: Topical HA may be used to increase the expressions of type I and III collagen, decrease the ratio of collagen type I/III, and enhance the biomechanics performances of transplanted skin.

[Expressions of endoplasmic reticulum stress associated proteins in livers of severely burned rats].

OBJECTIVE: To explore the expression of endoplasmic reticulum stress (ERS) associated proteins in livers of severely burned rats and examine its potential significance. METHODS: Sixty-four Wistar rats were randomly divided into the control and burn groups (30% total body surface area full-thickness thermal injury) (n = 32 each). Livers were harvested at Day 1, 4, 7, 14 post-burn. Western blot was used to detect the expressions of endoplasmic reticulum stress associated proteins glucose regulated protein 78 (GRP78), C/EBP-homologous protein (CHOP), active caspase-12 and active caspase-3. Hepatic apoptosis was assessed by the assay of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). RESULTS: Compared with the control group, the expression of GRP78 became elevated at Day 1, 4, 7, 14 post-burn (1.29 ± 0.11 vs 1.00 ± 0.00, 1.28 ± 0.12 vs 0.95 ± 0.16, 1.29 ± 0.14 vs 0.93 ± 0.06, 1.41 ± 0.17 vs 1.02 ± 0.13 respectively); the expression of CHOP was higher at Day 1, 4 (1.72 ± 0.07 vs 1.00 ± 0.00, 1.82 ± 0.18 vs 1.46 ± 0.08 respectively) while active caspase-12 and active caspase-3 increased at Day 1, 4, 7 post-burn (2.05 ± 0.65 vs 1.00 ± 0.00, 2.16 ± 0.69 vs 0.95 ± 0.21, 1.98 ± 0.56 vs 0.90 ± 0.22; 1.96 ± 0.15 vs 1.00 ± 0.00, 1.40 ± 0.14 vs 1.07 ± 0.12, 1.77 ± 0.17 vs 1.15 ± 0.21 respectively); the apoptotic index(%) of hepatocytes was higher at Day 1, 4, 7, 14 post-burn (27.20 ± 3.63 vs 5.00 ± 0.71, 16.40 ± 1.52 vs 5.40 ± 1.14, 27.60 ± 1.82 vs 7.40 ± 1.14, 10.20 ± 1.92 vs 5.20 ± 1.64 respectively). All results were statistically significant (all P < 0.05). CONCLUSION: ERS activates and expressions of associated proteins GRP78, CHOP, active caspase-12 and active caspase-3 increase in livers of severely burned rats.

[Effect of PRX-2 gene transferred by lipofectamine on the proliferation of human skin fibroblasts].

OBJECTIVE: To explore the effects of PRX-2 gene transferred by lipofectamine on the human skin fibroblasts. METHODS: Normal human skin fibroblasts were cultured and PRX-2 gene was transferred by lipofectamine. The proliferation of fibroblasts was detected by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and flow cytometry. RESULTS: The proliferation of PRX-2-transfected fibroblasts was stronger than that of normal counterparts. There were fewer cells during G0-G1 period and more cells during S and G2-M periods. The proliferative index increased. CONCLUSION: The proliferation of fibroblasts may be modified by transfected PRX-2. Thus PRX-2 plays an important role during the healing of human skin wound.

[Growth and migration of umbilical cord mesenchymal stem cells on polycarbonate membrane with different pore sizes].

OBJECTIVE: To observe the growth and migration of human umbilical cord mesenchymal stem cells (hUCMSCs) on polycarbonate membrane with different pore sizes and explore the criteria of selecting optimal Transwell insert for indirect co-culture to induce the differentiation of hUCMSCs. METHODS: hUCMSCs were isolated in vitro and then expanded in culture medium. After the treatment of mitomycin C, the cells were seeded on porous membranes of 6-well-dish Transwell inserts with different pore sizes of 0.4, 3.0 and 8.0 µm respectively. After culturing for 7 days, the cells were observed and counted on the bottom of each porous membrane. Then the calculation of migration ratio was performed. The growth and migration of hUCMSCs on porous membranes were also examined under scanning electron microscope (SEM). RESULTS: The migration ratios of hUCMSCs on membranes of 0.4, 3.0 and 8.0 µm pore sizes were 0, 1.8% and 8.0% respectively. The migration ratio of cells on 0.4 µm pore size membrane was statistically different from that of the other two pore size groups (P < 0.01). Under SEM, a small portion of cells were growing on the bottoms of membranes and moving through the pores. But there was no cell movement through 0.4 µm pore size membrane. CONCLUSIONS: hUCMSCs can migrate through the polycarbonate membranes of 3.0 µm and 8.0 µm pore sizes but not through the 0.4 µm one. Thus both sides of polycarbonate membrane of 0.4 µm pore size may be used for close indirect co-culture to induce the differentiation of hUCMSCs.

[Effects on collagen I and III after transplantation of porcine acellular dermal matrix with hyaluronic acid].

OBJECTIVE: To investigate the changes of collagens I and III after the addition of hyaluronic acid in the transplantation of porcine acellular dermal matrix. METHODS: Full-thickness skin defects were created on the dorsa of Japanese white rabbits. And the rabbits were divided randomly into 3 groups: Group A (hyaluronic acid, porcine acellular dermal matrix plus thin skin autografts), Group B (porcine acellular dermal matrix plus thin skin autografts) and Group C (skin autografts). Skin biopsies were performed at Day 50 post-grafting to detect the contents of collagens I and III by histological examinations, immunohistochemistry method and Western blot. RESULTS: The areas of skin graft were (13.3 ± 1.2), (9.5 ± 0.9) and (10.0 ± 1.4) cm(2) in Groups A, B and C respectively. Group A was larger than Groups B and C(all P < 0. 01). There was no statistical difference between Groups B and C (P > 0.05). The expressions of collagen I were 1894 ± 164, 515 ± 38 and 395 ± 43 in Groups A, B and C respectively. Group A was higher than Groups B and C (P < 0.01). And the expressions of collagen III were 5411 ± 435, 874 ± 70 and 2078 ± 175 in Groups A, B and C respectively. Group C was higher than Group B and yet lower than Group A (all P < 0.01). The ratios of collagen I and collagen III in Group A (0.39) and Group B (0.59) were higher than that of Group C (0.19) (all P < 0.01). CONCLUSION: The addition of hyaluronic acid may boost the expression of collagens I and III and decrease the ratio of collagen I/collagen III. Thus it facilitates wound healing and basilar membrane remodeling and alleviates the contraction of skin transplant.

[Early changes in serum neutrophil elastase in rats with burn, blast injury or combined burn-blast injury and its significance].

OBJECTIVE: To explore the early changes in serum neutrophil elastase (NE) in rats with burn, blast injury or combined burn-blast injury and its significance. METHODS: A total of 176 male Sprague Dawley rats were randomly divided into four groups: control (C), burn (BU), blast injury (BL) and burn-blast combined injury (BB). Rats in C group were not injured. Animals in BU group were subjected to 25% TBSA full-thickness burn on back with 94 degrees C water for 12 seconds; Animals in BL group were inflicted with moderate blast injury with 5 g 8701 compressed dynamite stick as the explosion source 75 cm away while left chest facing the explosive source; Rats in BB group were burned immediately after the blast injury similarly as in BL group. During the first 24 h post-injury, animals in BU and BB groups received intraperitoneal injection of sodium lactate Ringer's solution at a dose of 50 ml x kg(-1) x 12 h(-1). Protein concentration in bronchoalveolar lavage fluid (BALF), water content of lung tissue and NE content in serum were determined at 0 h (C group), 3 h, 6 h, 12 h, 1 d, 2 d, 3 d, 7 d post-injury. RESULTS: Protein concentration in BALF, water content of lung tissue and NE content in serum in SD rats of the injured groups were significantly higher than those in C group (P < 0.01 or P < 0.05), peaked within 2 d post-injury, especially at 2 d post-injury (NE content in serum: BU group, 319. 85 +/- 19.50 ng/ml; BL group, 467.43 +/- 31.64 ng/ml; BB group, 626.00 +/- 26.38 ng/ml vs. C group, 78.53 +/- 25.10 ng/ml). Overall, protein concentration in BALF, water content of lung tissue and NE content in serum in BB group were significantly higher than BU and BL groups (P < 0.01 or P < 0.05). Correlation analysis showed that within 3 d postinjury, a significant positive correlation was found between the protein concentration in BALF, water content of lung tissue and NE content in serum (r = 0.7910, 0.8078, P < 0.05) in BU group. NE content in serum and protein concentration in BALF were significantly positively correlated in BB group (r = 0.8672, P < 0.05). CONCLUSION: NE may play an important role in early lung injury of burn or blast injury, especially in combined burn-blast injury.

Plasma glucagon-like peptide 1 was associated with hospital-acquired infections and long-term mortality in burn patients.

BACKGROUND: Although glucagon-like peptide 1 levels have been closely associated with inflammation and mortality in septic patients, the clinical importance of glucagon-like peptide 1 on hospital-acquired infections and long-term mortality after burn injury remains unexplored. METHODS: Plasma samples from 144 burn patients were collected on admission to determine total glucagon-like peptide 1, interleukin 6, and monocyte chemotactic protein-1 levels. Hospital-acquired infections were determined by positive microbial culture. One-year mortality was assessed by telephone interview. Factors associated with glucagon-like peptide 1 were determined by multivariable linear logistic regression. Predicting the clinical importance of glucagon-like peptide 1 on the development of hospital-acquired infections and mortality were determined by Cox proportional hazards models and further by receiver operating characteristic curve analysis. Kaplan-Meier analyses were performed to examine whether the mean glucagon-like peptide 1 level of the cohort could discriminate the hospital-acquired infections-free survival. RESULTS: Median burn size was 41% (19%-70%) of total body surface area. Hospital-acquired infections developed in 36 (25%) patients after a mean of 10 ± 1 days after injury. Interleukin 6, monocyte chemotactic protein-1, and blood urea nitrogen levels and thrombin time were independently associated with increased glucagon-like peptide 1 levels. Levels of glucagon-like peptide 1 (median, interquartile range) were greater in patients who developed hospital-acquired infections than in those who did not (237 pmol/L, 76-524 vs 80 pmol/L, 51-158; P < .001) and in patients who died (536 pmol/L, interquartile range: 336-891 pmol vs 98 pmol/L, 47-189; P < .001). Although the glucagon-like peptide 1 level could not predict hospital-acquired infections-free survival in individual patients, it could predict 1-year mortality independently (P = .021). Moreover, a glucagon-like peptide 1 level of 200 pmol/L could discriminate hospital-acquired infections-free survival (P < .001). CONCLUSION: Admission glucagon-like peptide 1 level can discriminate hospital-acquired infections-free survival and predict long-term mortality in a group of patients with burn injury. Our data suggests that glucagon-like peptide 1 may be a predictive biomarker for hospital-acquired infections and mortality in burn patients.

Effects of Blast Wave-induced Biomechanical Changes on Lung Injury in Rats.

OBJECTIVE: To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances. METHODS: Simulate open-field shock waves; detect the biomechanical effects of explosion sources at distances of 40, 44, and 48 cm from rats; and examine the changes in the gross anatomy of the lungs, lung wet/dry weight ratio, hemoglobin concentration, blood gas analysis, and pathology. RESULTS: Biomechanical parameters such as the overpressure peak and impulse were gradually attenuated with an increase in the injury distance. The lung tissue hemorrhage, edema, oxygenation index, and pathology changed more significantly for the 40 cm group than for the 44 and 48 cm groups. The overpressure peak and impulse were significantly higher for the 40 cm group than for the 44 and 48 cm groups ( P < 0.05 or P < 0.01). The animal mortality was significantly higher for the 40 cm group than for the other two groups (41.2% vs. 17.8% and 10.0%, P < 0.05). The healing time of injured lung tissues for the 40 cm group was longer than those for the 44 and 48 cm groups. CONCLUSIONS: The effects of simulated open-field shock waves on the severity of lung injuries in rats were correlated with the injury distances, the peak overpressure, and the overpressure impulse.

Regulation of signaling pathways downstream of IGF-I/insulin by androgen in skeletal muscle of glucocorticoid-treated rats.

BACKGROUND: The mechanisms by which androgens ameliorate glucocorticoid-induced muscle wasting are still under investigation. In the present study, we tested the hypothesis that androgen's effects in reversing muscle wasting are related to activating the signaling pathways downstream of insulin-like growth factor-1 (IGF-I)/insulin. METHODS: Forty female Sprague-Dawley rats were randomly divided into four groups: control group, dexamethasone (DEX) group, testosterone (TES) group, and TES + DEX group. Each group was injected with saline or DEX (0.1 mg/100 g/d) for 10 days and sesame oil or TES (0.5 mg/100 g/d) for 13 days. Several downstream targets of IGF-I/insulin in skeletal muscle including protein kinase B (Akt), p70 ribosomal protein S6 kinase (p70S6K), and glycogen synthase kinase-3beta (GSK-3beta) that are associated with protein synthesis were examined. Two proteolysis-related ubiquitin E3-ligases, muscle atrophy F-box, and muscle RING finger-1 that are also regulated by IGF-I/insulin were also assessed. RESULTS: TES attenuated gastrocnemius muscle atrophy induced by DEX. TES prevented the DEX-induced decrease of IGF-I expression in gastrocnemius muscle, but not in serum. TES ameliorated DEX-induced dephosphorylation of Akt and p70S6K and promoted the phosphorylation of GSK-3beta in gastrocnemius muscle. The total amount of Akt, p70S6K, or GSK-3beta proteins was not changed among these groups. TES did not show any effects on the DEX-induced upregulation of muscle atrophy F-box, and muscle RING finger-1 mRNA in gastrocnemius muscle. CONCLUSION: This findings suggest that the effects of TES in reversing DEX-induced muscle atrophy are related to signaling pathways downstream of IGF-I/insulin that are associated with protein synthesis.

[The curative effect of 1.8% hypertonic electrolyte glucose solution in enteral resuscitation of burn shock].

OBJECTIVE: To study the resuscitative effect of hypertonic electrolyte glucose solution (HEGS) in enteral resuscitation of burn shock. METHODS: Eighteen Beagle dogs with 35% TBSA full-thickness flame injury were used in this study. They were randomized to a control group (no-fluid resuscitation, N group), a HEGS resuscitation group (H group) or an isotonic electrolyte glucose solution (IEGS) resuscitation group (I group). The solution enterally was given for resuscitation from half an hour after burn. The volumes and rates of fluid infusion in the H group were basically in accordance with 2 ml/(kg x 1%TBSA), those in the I group were basically in accordance with parkland formula [4 ml/(kg x 1%TBSA)]. The haemodynamic parameters, global end-diastolic volume index, plasma volume, osmotic pressure of plasma, intestinal absorptive rates of water and Na(+), and intestine mucosa blood flow were continuously assessed. RESULTS: The cardiac output index, global end-diastolic volume index, plasma volume and intestine blood mucosa flow reduced markedly after burn in the three groups, and then gradually returned from 2 h after burn in two resuscitation groups, which were higher than that in the N group (P < 0.05). The activities of diamine oxidase in plasma in the two resuscitation groups were higher than that in N group (P < 0.05). The intestinal absorption rates of water and Na(+) reduced markedly after burn in two resuscitation groups with the lowest levels, and then returned from 6 h after burn. The rates of water in H group were lower than that in I group (P < 0.05); the rates of Na(+) in H group were higher than in I group (P < 0.05). CONCLUSION: The results indicated that 35%TBSA III degrees burn-injury dogs be resuscitated effectively with 1.8% hypertonic electrolyte-glucose solution by enteral, which 1/2 volume of an isotonic electrolyte glucose solution.

[Effects of early oral fluid resuscitation on hemodynamic and tissue perfusion during shock stage in dogs with a 50% total body surface area full-thickness burn.].

OBJECTIVE: To investigate the effect of early oral fluid resuscitation on hemodynamic and tissue perfusion in dogs with severe burn shock. METHODS: Eighteen male Beagle dogs with intubation of carotid artery, jugular vein, stomach, jejunum and bladder for 24 h were subjected to a 50%TBSA full-thickness burn, then were equally divided into non fluid resuscitation (NR), oral resuscitation (OR) and intravenous resuscitation(IR) groups, (each n = 6). Dogs in IR and OR groups were given glucose-electrolyte solution (GES) by gastric tube or intravenous infusion according to Parkland formula within 24 h after burn, while those in NR group were not given any treatment. Dogs in each group were given intravenous fluid resuscitation from 24 h after burn. The mean arterial pressure (MAP), cardiac output (CO), systemic vascular resistance (SVR), dp/dt max of left ventricular contractility (dp/dt(max)), gastric carbon dioxide pressure (PgCO2), intestinal mucosal blood flow (IMBF), and urinary output were determined before burn (0 h) and 2, 4, 8, 24, 48 and 72 h after burn at no anaesthesia state. Mortality rate of 72 h after burn was also recorded. RESULTS: MAP, CO, dp/dt(max), IMBF greatly decreased, and SVR and PgCO2 obviously increased from 2 h after burn in each group (P < 0.01). The measurements except IMBF of IR group returned to pre-injury levels at 72 h after burn, while CO, SVR, PgCO2 and IMBF of OR group still worse compared with 0 h (P < 0.01). All measurements of NR group kept on worsen, and died with anuria within 24 h after burn. Parameters of hemodynamic and tissue perfusion of OR group were significantly superior to those of NR group, but it inferior to those of IR group. At 72 h after burn, 6 (6/6) survived in IR group, 3 (3/6) in OR group and 0 (0/6) in NR group. CONCLUSIONS: Although oral resuscitation with GES is not as efficient as intravenous resuscitation in a 50%TBSA burn injury, it still can promote hemodynamic, improve the tissue perfusion and reduce the mortality comparing to no resuscitation. Oral resuscitation might be an ideal alternative way of intravenous resuscitation, especially in wars or other site of mass casualties.

[Changes in proliferative activity of myoblasts and expression of Akt in skeletal muscle of rats after severe burn injury].

OBJECTIVE: To investigate changes in proliferative activity of myoblasts in skeletal muscle and potential role of phosphorylated Akt on it, so that a better understanding in mechanisms of skeletal muscle atrophy after burn injury will be got. METHODS: One hundred and twenty Wistar rats were randomly divided into 2 groups: control and severe thermal injury group. Rats in severe thermal injury group were subjected to a 40% total body surface area full-thickness scald injury, and Tibialis Anterior (TA) muscles were collected on 0, 1, 4, 7, 10, 14 days post-injury. After muscle mass determined, immunohistochemical double staining was used for detection of Proliferative Cell Nuclear Antigen (PCNA) of myoblasts. Protein expression of total Akt and phosphorylated Akt was determined by Western Blot. RESULTS: Burn injury induced significant reduction of TA muscle mass and maximal reduction of it appeared by 4 days after injury (P < 0.01). Proliferative activity of myoblasts decreased significantly from the first day post-injury (P < 0.01) and increased slowly to basal level of controls after 7 days post-injury. The phosphorylated Akt was undetectable in both of controls and injured samples before 4 days but increased significantly after 7 days post-injury (P < 0.01), though total Akt expression had no significant alteration at any time points (P > 0.05). CONCLUSIONS: Decrease in proliferative activity of myoblasts may be one of the contributors of significant atrophy of skeletal muscle after burn injury. Effect of phosphorylated Akt on proliferation attenuated in early stage and increased significantly in later stage after burn injury may partly explain the changes in proliferative activity of myoblasts.

[Preliminary study of skeletal muscle apoptosis after severe thermal injury in rats].

OBJECTIVE: To investigate changes in skeletal muscle apoptosis after a severe thermal injury in rats. METHODS: One hundred Wistar rats were randomly divided into two groups: sham thermal injury group and severe thermal injury group. They were subdivided into 1, 4, 7, 10, 14 days post-injury with 10 rats in each subgroup. Rats in severe thermal injury group were subjected to a 40% total body surface area full-thickness scald injury. Both weight and tibialis anterior (TA) mass of rats were weighed on 1, 4, 7, 10, 14 days post-injury. Electron microscope was used for observing ultrastructural changes in skeletal muscle, including apoptosis. Tissues of tibialis anterior from burn and sham burn animals were then examined by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistochemistry. RESULTS: Compared with sham thermal injury group, body weight and TA mass of rats were decreased from first day on, and it dropped to the lowest level at 4 days (P<0.05 and P<0.01), and started to regain from 7 days on (all P<0.01). Electron micrographs showed condensation of chromatin around the periphery of the nucleus, blebbing of the sarcolemma, and free of myofibrils near myonuclei in a large area in skeletal muscle of thermally injured rats. Sporadic TUNEL positive myonuclei were also seen under light microscope in skeletal muscle in thermal injury group. There were no characteristic signs of apoptosis in skeletal muscle in rats of sham group. CONCLUSION: There are skeletal muscle apoptosis after severe thermal injury. It may contribute to atrophy of skeletal muscle after burn injury in rats.

[Change in T cell-mediated immunity and its relationship with high mobility group box-1 protein levels in extensively burned patients].

OBJECTIVE: To investigate the change in T cell-mediated immunity and its relationship with plasma high mobility group box-1 protein (HMGB1) levels in severely burned patients. METHODS: Thirty-five extensively burned patients (> 30% total body surface area) were included in this study, and were divided into MODS group (n = 13) and non-MODS group (n = 22). The blood samples were collected on post burn days 1, 3, 5, 7, 14, 21 and 28. The plasma levels of HMGB1 were measured by using ELISA, and T lymphocyte proliferation response and its IL-2 production ability in peripheral blood were determined too. In addition, the ratio of CD4+/CD8+ T cells were detected by using flow cytometry. RESULTS: Plasma HMGB1 levels were markedly elevated on post burn day 1 in severely burned patients, and HMGB1 level was significantly higher in MODS group than in non-MODS group (P < 0.05). Lymph proliferation response and IL-2 production of T cells in peripheral blood, and the ratio of CD4+/CD8+ T cells in MODS group were markedly lower than those in non-MODS group on post burn days 1, 14, 21 and 28 (all P < 0.05). It indicated that plasma HMGB1 levels were negatively correlated to T cellular immune function parameters, including lymphocyte proliferation response, IL-2 production, and the ratio of CD4+/ CD8+ T cells in extensively burned patients (all P < 0.05). CONCLUSIONS: Extensive burns could lead to T cellular immune dysfunction, which appears to be associated with the development of MODS. HMGB1, as an important late mediators of inflammation, might be involved in the pathogenesis of suppression of T cell-mediated immunity in these patients.