Objective To investigate the influence of high + Gzenvironment on receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) messenger RNA (mRNA ) expression in the peri-implant bone tissue by an animal model. Methods Thirty New Zealand white rabbits were randomly and averagely divided into 3 control groups and 3 experimental groups corresponding to the investigation for 3 weeks ,5 weeks and 12 weeks respectively.Rabbits′ mandible incisors of both sides were extracted and im planted with 1 implant in each socket immediately.After 1 week of rest ,the experimental rabbits were exposed to high + Gzenvironment 3 times a week (Monday ,Wednesday ,Friday) ,The exposure scheme choose the + Gzprofile with 4～9 G for 10～45 s with 1 G/s onset rate and with the intervals of 1 min.The rabbits of control groups were not exposed to + Gzenvironment and normally fed.One control group and one experimental group rabbits were respectively sacrificed at the 3rd week (+Gzexposure for 2 weeks) , 5th week (+Gzexposure for 4 weeks) and 12th week (+Gzexposure for 4 weeks and normal feeding for 7 weeks) after the implanting surgery.The specimens were obtained to find the mRNA expression of RANKL and OPG by real-time polymerase chain reaction (RT-PCR) examination. Results The mRNA expression of RA NKL and OPG were the highest 3 weeks after the surgery in both groups , and then decreased gradually.The RANKL mRNA expression and the RANKL/OPG ratio of the experimental group were significantly higher than those of the control group 3 weeks after the surgery (P＜0.05).Five weeks after the surgery ,the OPG mRNA expression of the experimental group was significantlylowerthanthatofthecontrolgroup(P＜0.05),buttheRANKLmRNAexpressionand RANKL/OPG ratio were still higher than that of control group (P＜0.05).Twelve weeks after the surgery ,the differences on RANKL and OPG mRNA expressions was not obvious between two groups. Conclusions High +Gzexposure could increase the expression of RA N K L ,raise RA N K L/OPG ratio and promote bone resorption ,but may be not conducive to implant bone bonding.

Objective To investigate the influence of high + Gzenvironment on receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) messenger RNA (mRNA ) expression in the peri-implant bone tissue by an animal model. Methods Thirty New Zealand white rabbits were randomly and averagely divided into 3 control groups and 3 experimental groups corresponding to the investigation for 3 weeks ,5 weeks and 12 weeks respectively.Rabbits′ mandible incisors of both sides were extracted and im planted with 1 implant in each socket immediately.After 1 week of rest ,the experimental rabbits were exposed to high + Gzenvironment 3 times a week (Monday ,Wednesday ,Friday) ,The exposure scheme choose the + Gzprofile with 4～9 G for 10～45 s with 1 G/s onset rate and with the intervals of 1 min.The rabbits of control groups were not exposed to + Gzenvironment and normally fed.One control group and one experimental group rabbits were respectively sacrificed at the 3rd week (+Gzexposure for 2 weeks) , 5th week (+Gzexposure for 4 weeks) and 12th week (+Gzexposure for 4 weeks and normal feeding for 7 weeks) after the implanting surgery.The specimens were obtained to find the mRNA expression of RANKL and OPG by real-time polymerase chain reaction (RT-PCR) examination. Results The mRNA expression of RA NKL and OPG were the highest 3 weeks after the surgery in both groups , and then decreased gradually.The RANKL mRNA expression and the RANKL/OPG ratio of the experimental group were significantly higher than those of the control group 3 weeks after the surgery (P＜0.05).Five weeks after the surgery ,the OPG mRNA expression of the experimental group was significantlylowerthanthatofthecontrolgroup(P＜0.05),buttheRANKLmRNAexpressionand RANKL/OPG ratio were still higher than that of control group (P＜0.05).Twelve weeks after the surgery ,the differences on RANKL and OPG mRNA expressions was not obvious between two groups. Conclusions High +Gzexposure could increase the expression of RA N K L ,raise RA N K L/OPG ratio and promote bone resorption ,but may be not conducive to implant bone bonding.

BACKGROUND: Skin defect is commonly repaired by autologous skin graft, but in which, it is required healthy skin provider and it probably results in scarring deformity to various extents. The successful construction and clinical application of tissue-engineered skin (TE skin) mark the major breakthrough in treatment of skin defect.OBJECTIVE: To analyze the relationship between operation method and healing rate, through repair of skin defect with TE skin, to provide experimental evidence on clinical application of TE skin.DESIGN: Randomized controlled observation was designed.SETTING: Department of Oral and Maxillofacial Surgery, Teaching-Research Room of Histology and Pathology and Experimental Center of Tissue Engineering, School of Stomatology, Fourth Military Medical University of Chinese PLAMATERIALS: The experiment was performed in Experimental Center of Tissue Engineering, School of Stomatology, Fourth Military Medical University, in which 6 healthy York pigs were employed, of clean grade,aged varied from 2.5 to 3 months. 3 groups were randomized, named TE whole-layer group, TE dermal and auto-epidermal group and auto-graft group, 2 pigs in each group. 8 wounds were prepared in each pig, round in shape and 50 mm in diameter, 16 wounds in each group, totally 48wounds.METHODS: ①Preparation of TE whole layer and TE true skin. ② In TE whole-layer group: The whole layer of skin was cut off from fat layeralong the drawn line. When bleeding stopped thoroughly and the wound was covered with wet physiological saline gauze, TE whole-layer skin was collected and windowing was done on the skin for drainage. Physiological saline was used to rinsed away the culture solution on the surface of TE skin, and then, the cuticular layer was upward-covered the wound, avoiding gas vacuole between cuticular layer and wound. Single-layer oleic gauze, physiological saline gauze, aseptic dry gauze and elastic sponge cushion were covered successively, about 3-5 mm in thickness each layer. After routine dressing, elastic bandage was wrapped with compression terminally. ③ TE dermal and auto-epidermal group: The whole- layer skin was cut off with same method. Thin split-thickness skin (TIS) 0.1-0.2 mm was collected with drum dermanuring machine and soaked in physiological saline. The same method was used to collect the managed TE true skin and cover it on the wound, covering immediately on autoTTS. The rest management was same as TE whole-layer group. ④ Autograft group: The whole-layer skin was cut off and the fat tissue was removed, afterwards, it was re-grafted on the auto-wound, covered with various layers of dressing and bandaged with compression. ⑤ The survival case was determined if it was discovered no infection, necrosis and scaling of grafted skin, less than 3 mm in diameter when the wound was opened for changing fresh dressing each time, otherwise, the failed case was recorded. The survival rate in each group was analyzed statistically in 4 weeks after operation.MAIN OUTCOME MEASURES: Survival situation of grafted skin in 4weeks after operation in each group.RESULTS: In 4 weeks after operation, the survival rate of grafted skin was 75% in TE whole-layer group was 87% in TE dermal and auto-epidermal group and was 94% in auto-graft group. The results were similar basically in comparison among 3 groups (x2=-2.34, P ＞ 0.05).CONCLUSION: The effect of TE skin graft on repair of skin defect is near to that of auto-epidermal graft, testifying that the repair of skin defect with TE skin is feasible.