Objective:To observe the changes of c-jun expression in the monkey's temporalis muscles induced by stress reaction under +Gx loads.Methods:Nine male Rhesus macaques were randomly divided into four groups according to Gx loads and its lasting time:control group was exposed to +1 Gx/300 s overloads(n=2),and experimental groups 1(n=2),2(n=2)and 3(n=3)were exposed to +15 Gx/200 s,+21 Gx/165 s or +21 Gx/140 s respectively.Temporalis muscles tissue was fixed with 40 g/L buffered formaldehyde and embedded in paraffin.Histopathological changes were observed under light microscope.The expression of c-jun was detected by immunohistochemical PicTureTM method in the temporalis muscles.Results:Gross and histological analyses showed that no significant pathological changes in the temporalis muscles in different experimental groups.Immunohistochemical staining demonstrated that c-jun was over-expressed in the nuclei of the muscles in the experimental groups,while negative or slight positive staining was observed in the nuclei of muscles in control animals.There was no obvious difference of c-jun expression in different experimental groups.Conclusion:Overload gravity can induce enhanced expression of c-jun in temporalis muscles of the monkeys received +Gx loads.

BACKGROUND: Human periodontal ligament fibroblasts (HPLF) is the crucial cells in maintaining the configuration and function of periodontium. Adverse stress may cause HPLF to synthesize more inflammatory agents, which may cause the damage of periodontium.OBJECTIVE: To investigate the role of p38 MAPK of HPLF in the expres sion of inflammatory cytokine of interleukin-6 (IL-6) subjected to mechanical pressure, and explore the mechanism of the occlusal trauma to periodontium.DESIGN: A randomized and controlled trial.SETTING: Pathological Laboratory of the Fourth Military Medical Univer sity of Chinese PLA.MATERIALS: The HPLF were obtained from the middle part of 1/3 pe riodontium of 12 to 16-year-old youth whose 20 healthy permanent premo lar teeth should be extracted for orthodontic need. Main reagents and ap paratus: IL-6 enzyme-linked immunoabsorbent assay (ELISA) kit (Staff Room of Immunology of the Fourth Military Medical University of Chinese PLA); ELISA apparatus (Huadong Electronic Tube Factory); p38 MAPK specific inhibitor of SB203580 (produced by Biochemical Company, ob tained as a present from Professor Jiang, Staff Room of Pathophysiology, Southern Medical University).METHODS: The cells were primarily cultured till the 4-5 passages, and randomly divided into four groups: ①pressure-loading control group: the cell s were not subjected to pressure-loading and without pretreatment; ② pressure-loading group: the cells were subjected to continuous pressure-load ing (200 kPa) but without pretreatment; ③ pretreatment control group: the supernatant were added with 10 g/L dimathyl sulfoxide (DMSO, SB203580 solvent) at 1 hour before pressure-loading, the method and time of pressure loading were the same as those in the pressure-loading group; ④ pretreated group: the cells were pretreated with 1 μmol/L SB203580 (a specific in hibitor of the p38 MAPK) at 1 hour before pressure-loading, the method and time of pressure-loading were the same as those in the pressure-loading group. The cytosol and the supernatant in each group were sampled at 16 and 24 hours after pressure-loading respectively. The IL-6 expressions at different time points were detected with ELISA.MAIN OUTCOME MEASURES: The amount of IL-6 expression in HPLF induced by pressure with or without pretreatment by SB203580, a specific inhibiter of p38 MAPK.RESULTS: The expressions of IL-6 after continuous pressure-loading for 16 and 24 hours in the pressure-loading group were (143.1±0.42) and (49.46±1.01) ng/L, which were obviously higher than those in the pres sure-loading control group [(18.36±0.43), (18.78±0.50) ng/L, P ＜ 0.05]. The expressions of IL-6 after continuous pressure-loading for 16 and 24 hours in the pretreatment group were (56.39±0.72) and (21.52±1.39) ng/L, which were obviously higher than those in the pressure-loading control group [(137.96±0.54), (48.47±0.79) ng/L, P ＜ 0.05].CONCLUSION: p38 MAPK of HPLF acts as important cooperative mechanism to regulate IL-6 synthesis induced by mechanical pressure.

Objective:To investigate the relationship between pulp chamber height and dentine thickness of mandibular first molar on long axis with age in a Chinese Han population by cone-beam computed tomography(CBCT).Methods:CBCT images of 420 Chinese Han subjects(210 males and 210 females) were divided into 6 age groups as follows:15-24,25-34,35-44,45-54,55-64 and 65-74 years(n=70,35 males and 35 females).The height of pulp chamber and dentine thickness of the chamber root and floor of mandibular first permanent molar on long axis was measured by Galileo software of CBCT in vertical direction and then statistical analysis was carried out.Results:On long axis,the height of pulp chamber was (0.85±0.54) mm in males and (0.79±0.51) mm in females(P>0.05);dentine thickness of the pulp chamber roof was (3.60±0.49) mm in males and (3.50±0.49) mm in females(P>0.05);and dentine thickness of the pulp chamber floor was (2.57±0.52) mm in males and (2.49±0.5) mm in females(P>0.05).With aging,the height of pulp chamber was decreased(P<0.05) and dentine thickness of mandibular first permanent molar on long axis was increased(P<0.05).Conclusion:In Chinese Han population,the of pulp chamber height of mandibular first permanent molar on long axis is related to age,The dentine thickness increased with ages,the increase of dentine thickness of pulp chamber floor is more significant than that of the roof.