Objective:To investigate the bone resorption caused by osteoclasts and modulating functions of zinc ion on dental slices.Methods:Osteoclasts were separated from long-limb bones of neonatal rabbits,cultured with de-activated human tooth slices and glass slices.The cells in the experiment group were treated with 1?10~(-14)mol/L-1?10~(-4)mol/L zinc+10%(volume fraction) fetal calf serum(FCS)+?MEM,while those in the control group were grown in 10%FCS+?MEM.Osteoclasts on glass slices were stained by TRAP staining.The absorption pits on tooth slices were observed by inverted phase contrast microscope.The resorbing activity was evaluated with the concentration of calcium in the supernatant liquid of osteoclasts.The ratio between the concentration of calcium in the experiment group and that of the control group was termed the resorption index.Results: The isolated cells were multinuclear and showed positive in cytoplasma by TRAP staining.Usually,osteoclasts resorbed tooth slices first on the cementum and dentin,which had lower content of mineralized tissue.Compared with those on bone slices,the lacunae on the dental slices appeared less in amount,less in area and shallower in depth.They often showed shallow pits in a large area.Microscopy showed that the number and area of absorption pits formed on treated tissues were less than those on the control tissues.The content of calcium in the supernatant liquid increased at the concentrations of 1?10~(-4)-1?10~(-14)mol/L zinc,especially in the group of 1?10~(-8)mol/L,1?10~(-10) mol/L,1?10~(-14)mol/L zinc on the 3~(rd) day(P

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Objective: To study the origin, morphological structure, and functional regulation of osteoclast(OC) for further investigation on the mechanism and regulation of bone resorption. Methods: The OCs were isolated by two kinds of traditional method. Osteoclasts were isoclated from neonatal rat long bones. The cytochemistry was observed. The osteoclast-like cells (OLC) were derived from the mouse bone marrow cells in the presence of 1,25(OH)2VitD3 in vitro. Results: Both morphological and functional studies showed that the isolated cells shared some of the typical characteristics of osteoclasts, that is A. multinuclearity; B. developing spreading and pseudopodial activity when cultured on glass; C. high tartrate-resistant acid phosphatase (TRAP); D. resorption lacunae could be found when the cells were cocultured with devitalized bone slices and the number was increased as the time followed. OLC had the same histological and structural traits as the OCs by the former method. The concentration of Ca 2+ and acid phosphatase (ACP) increased gradually. Conclusion: Different kinds of method fit different experiments. The OC obtained by the first method has more activity of bone resorption. The OLC by the second method has more in quantity and can be used in the study of cell differentiation.

Osteoclasts were isolated mechanically from neonatal rat long bones and cultured on glass or devitalized human cortical bone slices. Both morphological and functional studies showed that the isolated cells were of typical osteoclasts, because; 1. they attached rapidly on the matrix and had pseudopodial activity when cultured on glass;2. they had multinuclei,most of them contained 3-10 nuclei;3. calci-tonin and clacitonin gene related peptide directly inhibited the cellular activity; 4. they showed high acid phosphatase activity; 5. resorption lacunae could be found when the cells cocultured with devitalized bone slices.

BACKGROUND: Based on a mouse model of tibial implantation, some scholars have found that the CaP-coated implant with recombinant human parathyroid hormone (1-34) (PTH(1-34)) shows strong osteogenesis effect at early stage, but this coating has not been applied in the oral environment.OBJECTIVE: To explore the role of local application of PTH(1-34) on immediate implant osseointegration . METHODS: Nine New Zealand white rabbits were randomly divided into two groups (six in experimental group and three in control group). All of the tooth sockets were filled with heterogeneous freeze-dried bone firstly after four incisors of each rabbit were extracted. In the experimental group, a titanium screw with PTH(1-34) loaded CaP coating was implanted into each tooth socket, while in the control group, a titanium screw with only CaP coating was implanted. The animals were executed respectively at 4, 8, 12 weeks after operation, and the intact maxillary and mandibular specimens were harvested and tested by gross observation, bone density analysis, torque test, histologic al observation, X-ray observation.RESULTS AND CONCLUSION: The gray value and maximum torque value of regenerated osseous tissue at different time points in the experimental group were significantly higher than those in the control group (P < 0.05). Within 4-12 weeks after implantation, regenerated and mature bone tissue appeared earlier in the experimental group than the control group. A large amount of new blood vessels were seen in the experimental group at 8 weeks after implantation, while in the control group, there were only few new blood vessels. To conclude, the local application of PTH(1-34) can promote bone formation, improve the implant-bone bonding strength, and enhance the stability of the implant.

BACKGROUND:Nanosilver has significant antibacterial properties, and nanohydroxyapatite has good biological activity and mechanical strength, while their mixture cannot only promote bone formation but also have antibacterial properties. OBJECTIVE:To observe the effect of nanosilver and nanohydroxyapatite mixed filing on the osseointegration of immediate implants. METHODS: Nine New Zealand white rabbits were randomly divided into experimental group (n=6) and control group (n=3) after four incisors from the upper and lower jaw were extracted. The mixture of nanosilver and nanohydroxyapatite was filed into the tooth socket in the experimental group, while nanohydroxyapatite was filed into the tooth socket in the control group. Titanium screw was immediately implanted into both groups. The intact maxila and mandibular specimens were harvested at the 4th, 8th, and 12th weeks after operation. Gross observation, X-ray bone density analysis, torque test and histological observation were conducted. RESULTS AND CONCLUSION:The gray value and maximum torque value of regenerated osseous tissue at different time points in experimental group were significantly higher than those in the control group (P < 0.05). Within 12 weeks of implantation, the bone formation rate and maturity of new bone tissue were higher in the experimental group compared with the control group, and no inflammatory cel infiltration occurred. At the 4th week after implantation, there was a large amount of inflammatory cel infiltration, and few inflammatory existed at the 8th week after implantation. These results demonstrate that compared with nanohydroxyapatite alone, the mixture of nanosilver and nanohydroxyapatite shows better antibacterial effect, biocompatibility and osteoinductive ability, which may accelerate osseointegration and promote osteogenesis.

Objective To investigate the diagnostic value of 1H magnetic resonance spectroscopy (1H-MRS) in mammary tumors and to discuss the technique factors which influence the detection rate.Methods The 1H-MRS features of 47 mammary tumors, of which 24 malignant tumors and 23 benign tumors confirmed by pathology were analyzed. All of the tumors were detected before Gd-DTPA enhancement. Results Eleven of 24 malignant tumors showed increased choline resonance peak at 3.24 ppm while 4 of 23 benign ones at 3.24 ppm .The positive value were 45.8% and 17.4% respectively. The sensitivity and specificity were 45.8% and 82.6% respectively by using 1H-MRS to discriminate benign from malignant tumors. The main factors influencing the detection rate were low suppressed lipid, low suppressed water and low single-noise rate.Conclusion Choline is not special features of malignant tumors. Choline can be obtained despite the nature of tumor if they grow rapidly. The low sensitivity of choline to be detected mainly dues to technique factors.

Objective To investigate the features and diagnostic value of MRI in prenatal and postpartum for placenta accreta. Methods 18 cases of placenta accreta confirmed by surgical pathologically and clinical were retrospectively analyzed,including 10 ca-ses of prenatal and postpartum 8 cases,observed the signal feature and diagnostic value of MRI images.Results In the 10 cases of prenatal patients with placenta accreta,MRI manifestations of 9 cases of placenta prevail,totally or partly covering cervical,10 cases of partial placenta and uterine muscle gap disappeared,boundaries are not clear,2 cases of uterine wall bars low signal-image inter-rupted,bulging outward placenta,increased sub placental vascular wag detected in 8 patients;8 cases of postpartum patients with pla-centa accrete,MRI show 4 examples which were mixed signals within the uterine cavity,with the junctional zone boundaries were not clear,the junctional zone was discontinuous interruption in 7 cases,8 cases of muscular layer appear oval,high and low,patchy mixed signals in shadow,4 cases in the palace district,5 cases of invading the shallow layer,3 cases of infection and deep muscle layers. Conclusion MRI technique is of great value for diagnosis of placenta accreta.

Objective To observe the effect of rapid reduction of physical activity on bone mass (BMC), bone mineral density (BMD)and bone metabolism in growing rats. Methods 48 male SD rats were divided into the high-intensity exercise group (T1, n=12), high tolow-intensity exercise group (T2, n=12), low-intensity exercise group (T3, n=12) and control group (Con, n=12). During the first 6 weeks,the rats in T1 and T2 group ran on treadmill with high intensity, while rats in T3 group took low-intensity treadmill exercise. 6 rats were sacrificedfrom each group at the end of 6th week. BMC, BMD of femur were measured with DEXA. Alkaline phosphatase (ALP), osteocalcin(BGP), tartrate-resistant acid phosphatase (TRACP) were detected with ELISA. The exercise intensity of T2 group was reduced rapidly to alow level as in T3 group, but remained in the other 2 groups. At the end of the second 6 weeks, the other rats were investigated again. ResultsCompared with the first measurements, ALP and BGP of the T2 group decreased significantly (P<0.05), and TRACP increased (P<0.05). There was no significant difference in BMC and BMD of femur (P>0.05). Conclusion Rapid reduction of physical activity can suppressbone formation and stimulate bone resorption of long bone among growing rats.

Objective To explore the effect of Taichi exercise on bone mineral density (BMD) of postmenopausal women. Methods 105 postmenopausal women were divided into Taichi group (n=54) and control group (n=51). BMD was detected with dual energy X ray absorptiometry (DXA) in both groups. Results The BMD of L1, L2 and shaft of femur were higher in Taichi group than in control group (P<0.05). The BMD of L4, left neck of femur and left wards triangle were significantly higher in the Taichi group than in the control group (P<0.01).The prevalence of postmenopausal osteoporosis (PMOP) was lower in the Taichi group (31.48%) than in the control group (39.22%), but there was no significant difference. The BMD of L1, L2 and shaft of femur, left wards triangle and shaft of femur were higher in postmenopausal women excising Taichi more than 5 years (P<0.05). Conclusion Long-term of Taichi exercise may increase the BMD of the postmenopausal women effectively and prevent the development of PMOP.