Objective: To explore the impact of personality and locus of control on job burnout.Methods: Chinese Maslach burnout inventory,Eysenck personality questionnaire and internal-external locus of control scale were used to examine 247 judges.Results: Introversion-extroversion was a significant predictor of exhaustion(P

BACKGROUND:Cytological studies show that bone marrow mesenchymal stem cel s play an important role in postmenopausal osteoporosis mechanism.
OBJECTIVE:To study the osteogenic differentiation in vitro of bone marrow mesenchymal stem cel s from ovariectomied osteoporotic rats.
METHODS:The osteoporotic animal model was established by performing ovariectomy in the 6-month-old female Sprague-Dawley rats. There were four groups:bone marrow mesenchymal stem cel s control group, bone marrow mesenchymal stem cel s osteoporosis group, bone marrow mesenchymal stem cel s osteogenic induction group and oseogenesis induction group. Bone marrow mesenchymal stem cel s were isolated from the rats of control group and oseogenesis induction group by means of the whole bone marrow adherence method and cultured to the 3rd generation. Then the bone marrow mesenchymal stem cel s were used in al the experiments. Cel morphology was observed under the inverted phase contrast microscope, cel cycle and proliferation index of bone marrow mesenchymal stem cel s were detected by flow cytometry. After osteogenic induction, the expression level of alkaline phosphatase was detected, and the fornation of calcium nodes of bone marrow mesenchymal stem cel s were marked by alizarin red staining.
RESULTS AND CONCLUSION:The cel s in the osteogenic induction group and oseogenesis induction group had the morphology of osteobalsts, and the change of morphology of the cel s in the oseogenesis induction group was relatively tardiness. The proliferation index in the control group was higher than that in the osteoporosis group (P<0.05);expression level of alkaline phosphatase in the osteogenic induction group was significantly higher than that in the oseogenesis induction group (P<0. 05), and the control group was significantly higher than the oseogenesis group (P<0.05). The alizarin red staining of the cel s in the osteogenic induction group was positive, while negative in the control group and the oseogenesis group;the staining in the osteogenic induction group was stronger than that in the oseogenesis induction group. These findings indicate that both the proliferative potential and the osteogenic potential of bone marrow mesenchymal stem cel s from the ovariectomized osteoporotic rats are decreased, which may be related with the ostoeporosis pathogensis of ovariectomied rats.

BACKGROUND: Vascular endothelial growth factor play an important role in promoting healing of osteoporotic fractures, but whether it can affect the bone mineral density is not clear. OBJECTIVE: To observe the correlation between serum vascular endothelial growth factor, bone mineral density and the number of osteoblasts in the ovariectomized rats. METHODS: Forty female Sprague-Dawley rats were randomly divided into ovariectomized group and control group. After 3 months, the bone mineral density of the whole body, femur and lumbar spine was measured. Rat enzyme-linked immunosorbent assay kit was used to measure the level of serum vascular endothelial growth factor. Then, the rats in two groups received femoral metaphyseal fixation, decalcified, dehydrated, embeding in paraffin, slicing and hematoxylin-eosin staining. Each slice was free to take five fields of view (10×40) in order to count the osteoblasts of femur distal metaphysis under optical microscope. RESULTS AND CONCLUSION: After ovariectomized for 3 months, the rats body mass was increased significantly (P < 0.05), and the bone mineral density of the whole body, femur and lumbar spine in the ovariectomized group was lower than that in the control group (P < 0.05), indicating the successful establishment of osteoporosis model. There was no significant difference in vascular endothelial growth factor level between the ovariectomized group and the control group (P > 0.05), and the difference of the osteoblast number between ovariectomized group and control group was not significant (P > 0.05). This indicated that there was no correlation between bone mineral density and the number of osteoblasts and vascular endothelial growth factor level in the ovariectomized group and the control group. These findings suggest that the bone mineral density is reduced and the body mass is increased in the ovariectomized rats, and the reduced bone mineral density of ovariectomized rats may be irrelevant with the change of serum vascular endothelial growth factor.

Objective To study the effects of chronic exposure to inorganic arsenic (iAs) in drinking water on bone mineral density (BMD) in mice and its underlying mechanisms.Methods Five-month-old female C57BL/6 mice were randomly divided into sham groups and ovarectomy (OVX) groups (n =19 mice each group),which were further randomly assigned into control group (distilled water) and iAs exposure groups [5 mg/L and 20 mg/L,inorganic arsenite (iAsⅢ):inorganic arsenate (iAsv) =1 ∶ 1].Following 3 months of exposure to iAs,BMD of the mice were determined by the dual energy X-ray detector.RAW 264.7 cell line and bone marrow hematopoietic stem cells (BMHSC) primarily isolated from C57BL/6 mice were used to study the in vitro effects of iAs on osteoclast differentiation and underlying mechanisms.During differentiation induced by receptor activator of nuclear factor-κ B ligand (RANKL,50 μg/L) and macrophage colony-stimulating factor (M-CSF,30 μg/L),RAW 264.7 cell line were treated with 0.00,0.25,0.50,0.75,1.00,1.50 μmol/L iAsⅢ,while BMHSC with 0.0,0.2,0.4,0.6,0.8,1.0 μmol/L iAsⅢ for 6 days.Based on the effect of iAsⅢ on the differentiation of RAW cells,RAW 264.7 cell line were treated by 0.6 μmol/L iAsⅢ combined with 0,5,10 mmol/L of N-acetyl-cysteine (NAC).Tartrate resistant acid phosphatase (TRAP)-positive red-colored cells with 3 or more nuclei were considered mature osteoclast.Results The femoral BMD of the mice [(80.04 ± 4.06) mg/cm2] that had been exposed to 20 mg/L of iAs for 3 months was substantially decreased compared to that of sham control mice [(84.44 ± 4.40) mg/cm2].As expected,the BMD of the OVX group [(76.36 ± 3.36) mg/cm2] was significant decreased compared to that of the sham control group (P ＜ 0.05).However,the BMD among the OVX groups showed no significant difference [5 mg/L:(77.74 ± 4.91) mg/cm2;20 mg/L:(75.56 ± 3.71) mg/cm2,P ＞ 0.05].In vitro studies,the iAsⅢ evidently affected the osteoclast differentiation in a concentration-dependent fashion.Low concentrations of iAs Ⅲ exposure significantly augmented osteoclast differentiation in the two cell models while high concentrations showed inhibitory effect.In RAW 264.7 cells,the number of osteoclasts in different groups was significantly different (F =1 522,P ＜ 0.05),in the 0.50 μmol/L iAs Ⅲ group the number of osteoclasts reached the peak.In the BMHSC,the nmnber of osteoclasts in different groups was also significantly different (F =1 781,P ＜ 0.05),in the 0.6 μmol/L iAsⅢ group the number of osteoclasts reached the peak.NAC pretreatment significantly abolished low-level iAsⅢ(0.6 μmol/L)-induced augmentation of osteoclast differentiation in a concentration-dependent fashion (0 mmol/L:109.33 ± 3.06;5 mmol/L:56.00 ± 2.65;10 mmol/L:22.67 ± 0.58,F =1 940,P ＜ 0.05).Conclusions The inhibitory effect of iAs on bone metabolism is dependent on the availability of ovary function,suggesting that iAs may interfere with estrogen metabolism and/or function to disturb bone metabolism.Oxidative stress induced by iAs exposure stimulates osteoclast differentiation,and the increased osteoclast differentiation may be involved in the reduction of BMD caused by chronic iAs exposure.These preliminary findings suggest that antioxidant intervention may be an effective approach to prevent osteoporosis induced by chronic iAs exposure.