PURPOSEThis study aims to explore the biomechanical mechanism of lower limb injuries to the driver by establishing a finite element (FE) simulation model of collisions.

METHODSFirst a minibus FE model was integrated with a seat belt system. Then it was used to rebuild two collisions together with the total human model for safety (THUMS) provided by Toyota Motor Corporation: a rear-end collision between a minibus and a truck and a head-on collision of a minibus to a rigid wall. The impact velocities of both collisions were set at 56 km/h. The vehicle dynamic response, vehicle deceleration, and dashboard intrusion in the two collisions were compared.

RESULTSIn the minibus rear-end truck collision, the peak values of the von Mises equivalent stress at the tibia and the femur were 133 MPa and 126 MPa respectively; while in the minibus head-on rigid wall collision, the data were 139 MPa and 99 MPa. Compared with the minibus head-on rigid wall collision, the vehicle deceleration was smaller and the dashboard intrusion was larger in the minibus rear-end truck collision.

CONCLUSIONThe results illustrate that a longer dashboard incursion distance corresponds to a higher von Mises equivalent stress at the femur. The simulation results are consistent with the driver's autopsy report on lower limbs injuries. These findings verify that FE simulation method is reliable and useful to analyze the mechanisms of lower limb injuries to the driver in minibus frontal collisions.

Accidents, Traffic ; Automobile Driving ; Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Lower Extremity ; injuries

OBJECTIVETo investigate the effect of the environmental carcinogenic factor-TCDD (2, 3, 7, 8-tetrachlorodibenzo-p-dioxin) on cell apoptosis and gene regulation of insulin-like growth factor binding protein 6 (IGFBP-6) in osteogenic sarcoma (SaOS-2) cells.

METHODSThe SaOS-2 cells were cultured with TCDD (1 x 10(-9), 1 x 10(-8), 1 x 10(-7) mol/L) for 24 hours. The MTT reduction assay and flow cytometry were used to measure the cell proliferation and the cell apoptosis in TCDD-treated SaOS-2 cells. The Nitrophenol phosphate salt method was used to measure activity of alkaline phosphatase (ALP) in SaOS-2 cells. The IGFBP-6 mRNA and protein in SaOS-2 cells were detected by reverse transcription polymerase chain reaction (RT-PCR) and western blotting analysis.

RESULTSSaOS-2 cell proliferation was up-regulated with TCDD (1 x 10(-9), 1 x 10(-8), and 1 x 10(-7) mol/L) about 20%, 47% and 93% (18.4 +/- 4.5, 22.5 +/- 3.6 and 29.4 +/- 4.2), respectively. The synthesis of ALP was up-regulated about 28%, 95%, and 142% (1.12 +/- 0.28, 1.58 +/- 0.14 and 1.96 +/- 0.17), respectively (P < 0.05). The cell apoptosis was down-regulated in dose-dependent biological manner about 5%, 26% and 52%, respectively (P < 0.05). The expression of IGFBP-6 mRNA and protein was decreased in 1 x 10(-7) mol/L TCDD-treated SaOS-2 cells about 76% and 72% (P < 0.05).

CONCLUSIONTCDD at low concentration may have the negative effect on cell apoptosis and down-regulation on gene expression of IGFBP-6 in SaOS-2 cells.

Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Insulin-Like Growth Factor Binding Protein 6 ; genetics ; metabolism ; Osteosarcoma ; metabolism ; pathology ; Polychlorinated Dibenzodioxins ; toxicity ; RNA, Messenger ; genetics

OBJECTIVETo evaluate the effects of retinoic acid (RA) on expression of bone morphogenetic protein 7 (BMP-7) in rat fetus with cleft palate, and the effects of RA on proliferation and apoptosis of osteoblasts.

METHODSAll-trans RA (ATRA) was used to induce congenital cleft palate in Wistar rat BMP-7 mRNA expression in maxillary bone tissue of fetal rats was measured by Northern blotting analysis. Flow cytometry and MTT assay were used to measure the apoptosis and proliferation of ATRA-treated MC-3T3-E1 cells. BMP-7 mRNA and protein expressions in ATRA-treated MC-3T3-E1 cells were detected by RT-PCR and Western blotting analysis.

RESULTSATRA could induce cleft palate of rat fetus. The incidence rate of cleft palate induced by 100 mg/kg AT-RA (45.5%) was significantly higher than 50 mg/kg ATRA (12.5%, P < 0.05). BMP-7 mRNA expression decreased in maxillary bone tissue of rat fetus with cleft palate. MC-3T3-E1 cells proliferation treated with 1 x 10(-6) mol/L ATRA decreased by 60%, the cell apoptosis increased by 2 times. BMP-7 mRNA and protein levels in MC-3T3-E1 cells treated with 1 x 10(-6) mol/L ATRA decreased by 60% and 80%, respectively, compared with ATRA-untreated cells (P < 0.05).

CONCLUSIONSBMP-7 may play an important role in embryonic palate development RA may possess the ability to down-regulate cell proliferation through regulation of BMP-7 gene expression.

3T3 Cells ; Animals ; Apoptosis ; drug effects ; Base Sequence ; Blotting, Northern ; Bone Morphogenetic Protein 7 ; genetics ; Cell Proliferation ; drug effects ; Cleft Palate ; genetics ; DNA Primers ; Down-Regulation ; drug effects ; Female ; Mice ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction ; Tretinoin ; pharmacology

We detected Zika virus (ZIKV) in a febrile case returning from Suriname and entry China from Guangzhou Baiyun International Airport Port.Serum and saliva samples were collected from a suspected case returning from Suriname.We detected ZIKV RNA using real-time fluorescence RT-PCR methods by both in-house reagent and commercial detection kits.RT-PCR detection was carried out with saliva sample and sequence analysis was performed.Phylogenetic tree was constructed to analyze the source of imported cases.Real-time fluorescent RT-PCR result showed that saliva was detected ZIKV RNA positive while for serum was weakly positive.A specific 1 500 bp fragment in size was amplified with saliva sample by RT-PCR.Sequence analysis showed 99％ homologous to the corresponding sequence of Brazil ZIKV (GenBank No.KX197250).Phylogenetic tree indicated it was located on African lineage.According to the epidemiological investigation results,clinical manifestations and nucleic acid detection of case,the suspected case was confirmed to infect Zika virus,being the first case from Suriname into Guangdong Province.

OBJECTIVETo investigate the influence of inhibition of stress on the survival rate, organ dysfunction and (Th)1/Th2 cytokine profiles of the rats with invasive infection in the wound at early postburn stage.

METHODSSprague-Dawley rats inflicted with 30% TBSA full thickness burn were randomly divided into A (n = 36, with immediate resuscitation), B (n = 36, with immediate resuscitation and lytic cocktail administration). After subeschar injection of 0.1 ml Pseudomonas aeruginosa (10(8) CFU/ml) on 3rd postburn day, the subeschar bacterial quantitative analysis, the survival rate at 96 hours after bacteria injection, the parameters of organ dysfunction and the mRNA expression of IL-2, IL-4, IL-10 and IFN-gamma were determined by corresponding methods.

RESULTSThe quantity of subeschar bacteria was larger than 1 x 10(5)/gram in both groups. The survival rate in B group (66.7 +/- 2.6)% was obviously higher than that in A group (33.3 +/- 1.7)%, (P < 0.01). Inflammatory infiltration and pathological changes in the internal organs in B group were alleviated obviously compared with A group. The expression of IL-2 mRNA in B group was significantly lower than that in A group before bacterial inoculation, but increased at 48 and 96 hours after bacterial inoculation, while it was lowered in A group at the same time points (P < 0.05). The expression of IFN-gamma mRNA in A group was significantly lower than that in B group (P < 0.01), while that of IL-4 and IL-10 mRNA in A group was evidently higher than that in B group (P < 0.05 approximately 0.01).

CONCLUSIONInhibition of the stress response during early postburn stage could be beneficial to the prevention of the bacterial invasion due to the changes in Th1/Th2 ratio.

Animals ; Burns ; metabolism ; microbiology ; Disease Models, Animal ; Interferon-gamma ; metabolism ; Interleukin-10 ; metabolism ; Interleukin-2 ; metabolism ; Interleukin-4 ; metabolism ; Pseudomonas Infections ; immunology ; Rats ; Rats, Sprague-Dawley ; Th1 Cells ; metabolism ; Th2 Cells ; metabolism ; Wound Infection ; therapy

OBJECTIVETo investigate the protective effect of inhibition of stress (lytic cocktail) on lung injury in severe burn rats at early stage.

METHODSSprague-Dawley rats inflicted with 30% TBSA full-thickness burn were randomly divided into A group (n = 36, fluid resuscitation with administration of lytic cocktail), B group (n = 36, fluid resuscitation only). Lung function was evaluated by partial pressure of oxygen (PaO2) in arterial blood and histopathologic changes on 3, 5, 7, 10 post burn day (PBD). The levels of malonyldialdehyde (MDA), myeloperoxidase (MPO), tumor necrosis factor-alpha(TNF-alpha) and interferon-gamma (IFN-gamma) in lung tissue were measured at the same time points.

RESULTSThe PaO2 level in A group on 3 PBD (12.58 +/- 0.41 kPa) was significantly higher than that in B group (8.86 +/- 0.23 kPa, P < 0.01). Compared with those in B group, the levels of MDA and MPO were significantly decreased in A group at each time point (P < 0.05 or 0.01), the levels of TNF-alpha on 3, 5, 7 PBD (P < 0.05 or 0.01) and IFN-gamma on 5, 7, 14 PBD (P < 0.01) were also decreased in A group. Swollen lung mesenchyme was alleviated, infiltration of inflammatory cell was lessened in A group.

CONCLUSIONLytic cocktail combined with immediate fluid resuscitation can inhibit stess response, downregulate the expression of inflammatory factor, ameliorate lung function in severe burn rat at early stage.

Animals ; Burns ; complications ; therapy ; Fluid Therapy ; Interferon-gamma ; metabolism ; Lung Injury ; etiology ; metabolism ; therapy ; Malondialdehyde ; metabolism ; Meperidine ; therapeutic use ; Peroxidase ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo explore the influence of L-arginine supplementation on the plasma amino acid spectrum in burn patients.

METHODSTen 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.

RESULTSThe 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).

CONCLUSIONThe 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.

Adolescent ; Adult ; Amino Acids ; blood ; Arginine ; therapeutic use ; Burns ; blood ; drug therapy ; Female ; Humans ; Male ; Parenteral Nutrition ; Wound Healing

OBJECTIVETo investigate the rule and possible mechanism of epidermal proliferation in wound edge of deep partial thickness scald injury in rat.

METHODSTwenty-four Sprague-Dawley rats inflicted with deep partial thickness scald were randomized into pre-scalding, 3 post-scalding day (PSD), 7PSD and 14PSD groups, with 6 rats in each group. Skin specimens from the wound edge were harvested for the observation of the histological characteristics of the epidermis. Cell cycles of epidermal cells were analyzed with flow cytometry. The expressions of cyclin D1, cyclin B1, cdk4 and the histone H1 kinase activity of MPF in epidermal cells were determined by Western blotting.

RESULTSAugmentation of nuclei and nucleoli was found in the epidermal cells from the wound edge in 3PSD group, while increased number of epidermal cells with obviously augmented nuclei and nucleoli were found in 14PSD group. The percentage of the cells in S phase increased in 14 PSD group. The percentage of epidermal cells in G2/M phase began to increase in 3PSD group, and that in 7PSD (4.5 +/- 0.6) and 14PSD (5.4 +/- 1.0) groups were obviously higher than that in pre-scalding group (2.9 +/- 1.1, P < 0.05). The expression of cyclin D1 increased significantly in 3PSD group. The expression of cdk4 decreased in 3PSD group, but began to increase in 14PSD group. There was no difference in the expression of cyclin B1 among groups. The MPF activity was significantly increased in 14PSD group.

CONCLUSIONThere was enhanced DNA synthesis and mitosis in epidermal cells of rats with deep partial scald during early post-scald stage, and active proliferation of epidermal cells was observed on 14PSD. The expression of cyclinD1/cdk4 complex and the activity of MPF increased since 14PSD, indicating that there was a special regulative pattern during wound healing.

Animals ; Burns ; pathology ; Cell Cycle ; Cell Proliferation ; Disease Models, Animal ; Epithelial Cells ; cytology ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Soft Tissue Injuries ; pathology ; Wound Healing

OBJECTIVETo investigate the possible mechanism of L-arginine supplementation on the angiogenesis of burn wounds in diabetic rats.

METHODSOne hundred male Sprague-Dawley (SD) rats were used in the study and were randomly divided into A (scalding control, n = 25), B (scalding of the rats with diabetes, n = 25), C (L-glycine control, n = 25) and D (L-arginine supplementation, n = 25) groups. Diabetes was produced by intra-peritoneal injection of streptozotocin (STZ) in B, C and D groups. The rats in C and D groups were gavaged with L-glycine and L-arginine in dose of 200 mg.kg(-1).d(-1), respectively. The glucose content of the back skin tissue was determined for five rats in each group eight weeks after STZ administration. Deep partial thickness scalding of 20% TBSA was engendered on the back in the other 80 rats. The wound area, wound healing rate, and microvascular density with CD34 immunohistochemistry staining were determined on 3rd, 7th, 14th, and 21st post scalding days (PSDs), In addition, the amount of nitric oxide (NO) released from the wound tissue and the tissue contents of vascular endothelial growth factor (VEGF) and transforming growth factor beta1 (TGF-beta1) from wound were determined at the above time points.

RESULTSCompared to those in group B, the wound healing rate in group D increased significantly since the 7th PSD [(44.10 +/- 3.50)%, P < 0.05], and the wound MVD value was increased significantly at all postburn time points. Furthermore, the levels of VEGF, NO and TGF-beta1 in the wound tissue was also increased significantly, while the glucose content in the cutaneous tissue was decreased to (1.380 +/- 0.120) mg/g.

CONCLUSIONL-arginine supplementation could be beneficial to the angiogenesis in the burn wound of the rats with diabetes, as well as to wound healing by increasing the synthesis and the release of VEGF, NO and TGF-beta1 from burn wound and by decreasing the glucose content in the cutaneous tissue of diabetic rats.

Animals ; Arginine ; therapeutic use ; Blood Glucose ; metabolism ; Burns ; metabolism ; therapy ; Diabetes Mellitus, Experimental ; metabolism ; therapy ; Male ; Neovascularization, Physiologic ; drug effects ; Nitric Oxide ; metabolism ; Rats ; Rats, Sprague-Dawley ; Transforming Growth Factor beta1 ; metabolism ; Vascular Endothelial Growth Factor A ; metabolism ; Wound Healing ; physiology

OBJECTIVETo investigate the biological characteristics of dermal fibroblasts of the diabetic rats with deep partial thickness scald, and to explore its relationship with delayed wound healing due to diabetes.

METHODSSprague-Dawley rats weighing 250 g were randomly divided into control (NM, n=40) and STZ-induced diabetic (DM, n=50) groups, and then deep partial thickness scald involving 10% TBSA were reproduced in the two groups. Skin samples were harvested from the wounds on 0, 3, 7, 14 and 21 post scald day (PSD) for the determination of certain histological characteristics.

RESULTSThe thickness of dermis layer in DM group before injury was obviously thinner than that in NM group (P < 0.01). There was an infiltration of a large amount of chronic inflammatory cells and increased content of cutaneous glucose in the dermal tissue in DM group (2.77 mg/g) compared with 0.85 mg/g in NM group, (P < 0.01). An accumulation of advanced glycation end products (AGEs) was found in the dermal tissue in DM group. After the scalding, the percentage of fibroblasts in S phase and hydroxyproline synthesis in DM group was evidently lower than those in NM group. But the apoptosis rate of fibroblasts was much higher in DM group than that in NM group (P < 0.05 or 0.01).

CONCLUSIONIt is found that the high contents of glucose and AGEs in diabetic skin exert untoward effects on biological characteristics of dermal fibroblast, probably constituting one of the underlying mechanisms of delay wound healing of scald in diabetic rats.

Animals ; Burns ; metabolism ; pathology ; Diabetes Mellitus, Experimental ; Fibroblasts ; cytology ; Glycation End Products, Advanced ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Skin ; metabolism ; pathology ; Wound Healing