Objective:To determine whether the immortalized human odo nt oblast-like cell line hTERT-hOd-l has transformed phenotype. Methods: The tumorigenicity, anchorage-independent growth, serum dependence and contact inhibition of the immortalized human odontoblast-like cell line hTERT- hOd-l were observed during continuous culture in vitro. Results: The cells showed to be nontumorigenic in nude mice, and to have no anchorag e-independent growth. The cells maintained the normal serum dependence and cont act inhibition. Conclusion:hTERT-hOd-l is a normal cell line w ithout obvious transformed phenotype.

Objective:To investigate if transforming growth factor-?1 (TGF-?1) induces apoptosis in odontoblast cell line MDPC-23. Methods:MDPC-23 cells were treated with TGF-?1 at 0.5,2.5 or 10 ng/ml for 48 h,apoptosis of MDPC-23 cells was detected by annexin V and propidium iodide (PI) staining, cell death detection ELISA and DNA electrophoretic analysis. Results: Consistent results were obtained from three different methods.TGF-?1 at 0.5-10 ng/ml induced apoptosis of MDPC-23 cells in a dose-dependent manner. Conclusion:TGF-?1 may paly a role in apoptosis of odontoblasts.

Objective: To investigate the root canal curvatures of anterior teeth in the Han nationality in Shaanxi province.Methods:392 permanent anterior teeth were examined by indirect digital radiography both from labiolingual and mesiodistal directions according to Schneider method, root canal curvatures were analyzed by electronic rule.Results:Root canals of the anterior teeth were mainly of type I. High rate of root canal curvature was found in maxillary canines (68.5%), and most of curves were in the apical third. There was a relationship between the root canal curvatures of maxillary canine and age(P=0.03). Conclusion:Root canal curvatures of maxillary canine are complicated,especially in maxillary canines. The root canal curvatures of maxillary canine decreased with aging.

Objective: To examine the effect of mouthwashing before dental procedure on environmental pollution of microorganism in dental clinic. Methods: Air samples in dental clinic after tooth preparation whether using mouthwashes or not pre operationally were collected and cultured with blood agar plates, the bacteria colonies formed on the plates in different groups were counted as the index for air contamination. Results: Environmental contamination from tooth preparation in dental clinic could be reduced significantly by using mouthwash pre operationally( P 0.05), but the size of the colonies formed on the plates in Kou Jie Su group was smaller than that in drinking water group. Conclusion: Environmental contamination from tooth preparation in dental clinic can be reduced by using mouthwash pre operationally. Combination of the pre operational mouthwashing with vacuum aspirator or ventilation installation may be a better way to control the possible cross infection in dental clinic.

Objective:To examine the polymerization shrinkage stress of three universal hybrid composite resins by photo-elastic analysis.Method:Epoxide resin disks (d=80 mm,h=4 mm) with a cylindrical cavity (d=4 mm) in the middle were prepared.Composite resins of Charisma,TPH Spectrum and Esthet-X were respectively filled in the cavities for the formation of specimens.Eight specimens were made for each resin.The resin specimens were light cured for 40 s by Dentsply QHL75 Curing lite. Polymerization contraction stress was calculated based on the diameter of the isochromatic rings of first order obtained from the diameter of epoxide resin specimen at 1,2,3,4,5,10,20 and 30 min,1,24 and 48 h after curing. The statistical analysis was carried out with the Wilcoxon test.Results:Polymerization contraction stress rised rapidly in the first 10 min after curing. 1 and 24 h after curing the shrinkage stress(MPa) of Charisma were 2.893 6?0.1 and 4.190 4?0.1,while that of Esthet-X were 2.291 7? 0.1 and 3.143 9? 0.3 ,respectively.The shrinkage stress values of TPH spectrum was between those of Charisma and Esthet-X 24 h after curing. 79% specimens showed shrinkage stress releasing during 24 and 48 h after curing.Conclusion:The rates of the shrinkage stress of the three studied resin composites are different.

Objective:To clone and sequence cDNA of MH2 domain of Smad1 gene from human dental papilla cells. Methods:Total RNA was isolated from primarily cultured human dental papilla cells and reversely transcribed into single stranded cDNA.The desired DNA product was obtained by PCR with two gene specific primers.The segment was inserted into PUC19 vector and the plasmid was transformed into E.coli JM109.The double stranded cDNA of positive clone was sequenced.Results:The sequence of MHz domain of Smad1 cloned from human dental papilla cells was consistent with that reported by Hoodless et al. Conclusion:Smad1 exists in human dental papilla cells,BMP signaling may be mediated by smad1 in human dental papilla cells.

Objective To study the changes of apoptosis and cell cycle progression of Hela cells after the poly(ADP-ribose) polymerase(PARP) was inhibited by its inhibitor 3-aminobenzamid(3-AB) and the mechanisms of PARP interaction with Hela cells damaged by irradiation.Methods Hela cell line was used.Flow cytometry(FCM) was used to examine the PARP expression of control and 3-AB groups at 0,2,4,8,12 h after administration with 5 mmol?L-1 3-AB.The percentage of apoptotic cells and cell cycle progression of control,irradiation,3-AB plus irradiation groups were measured with FCM at 2,8,12,24 h after exposure to 2 Gy irradiation following administration with 5 mmol?L-1 3-AB.Results The percentage of Hela cells with positive expression of PARP protein decreased after administration with 3-AB and there was significant difference between 3-AB plus irradiation group and control group(P

Objective To explore the effects of 75 mGy irradiation on the apoptosis of spermatogenic cells and antioxidant capacity of serum and testis and hormone levels in male rats with diabetes mellitus(DM).Methods Rats were injected intraperitoneally with streptozotocin(STZ)to develop diabetes.The diabetic rats were irradiated with 75 mGy X-rays every other day for 4 weeks.Their survival rate and body weight were recorded 12 weeks after development of diabetes.The apeptosis percentage of germ cells was measured with flow cytometry and TUNEL method.The changes of anti-oxidation and gonadal hormone levels in serum and testis were measured with kits.Results After the rats suffered from diabetes for 12 weeks,the survival rate in DM group was 25%(6/24),100% in normal control group(16116).The survival rate in 75 mGy + DM group(9/16,56.25%)was obviously higher than that in the DM group(X2= 4.00,P < 0.05).Meanwhile,the percentage of apaptotic spermatogenic cells in the diabetic rats was significantly larger than those in the normal control and irradiation groups(F = 5.496,P < 0.05).MDA and NO levels in serum and testis of diabetic rats were higher in varying degrees than that in the normal control,while the serum and testis MDA content in the 75 mGy + DM group were lower than those in the DM group especially in the testis(F = 10.644,P < 0.01).75 mGy X-ray irradiation decreased NO content in the diabetic rats serum significantly(F = 14.379,P < 0.05)and increased NOS activity and TS,FSH level(F = 9.676,43.194 and 5.282,respectively,P < 0.05 and P < 0.01).Conclusions LDR could decrease the MDA level and NO content,and increase the antioxidant enzyme activity and TS and FSH levels in testis and serum of diabetic rats.

Objective To explore the mechanism of radio-resistance of breast cancer stem cells by investigating the effects of ionzing radiation on the reactive oxygen species (ROS),apoptosis and cycle distribution.Methods The breast cancer MCF-7 cells were suspension cultured in serum-free medium containing a variety of growth factors. There were MCF-7 (breast cancer cells),MCF-7-S (breast cancer stem cells),MCF-7+8 Gy and MCF-7-S+8 Gy groups in the experiment. 4-24 h after 8 Gy irradiation, the ROS levels, percentages of apoptotic cells and percentages of the cells at each cycle phage were measured by FCM with 2′, 7′-dichlorodihydrofluorescin diacetate (DCFH-DA ), Annexin Ⅴ-FITC/PI and PI staining, respectively. Results The breast cancer stem cell microsphere accumulated hundreds of cells were obtained successfully at 7 d after suspension culture with serum-free medium containing a variety of growth factors;the FCM results showed that CD44+CD24- phenotype breast stem cells were up to 75.20%.With the time prolongation,the ROS levels and apoptosis in MCF-7 group and MCF-7-S group showed increasing trendency, and reached for the maximum values at 12 and 24 h;the ROS levels in MCF-7-S group were significantly lower than those in MCF-7 group at 4,8,12 and 24 h (P<0.05 or P<0.01), and the percentage of apoptotic cells in MCF-7-S group was significantly higher than that in MCF-7 group only at 8 h(P<0.05);the ROS levels (4,8,12 and 24 h)and percentage of apoptotic cells(12 h)were significantly increased in MCF-7+8 Gy group (P<0.05),and the percentages of apoptotic cells (4,8,12 and 24 h)in MCF-7-S +8 Gy group were significantly decreased (P<0.05 or P<0.01),but the ROS levels had no obvious change in MCF-7-S+8 Gy.At 12 h,as compared with MCF-7 group,the percentages of the cells at G0/G1 phase and G2/M phase in MCF-7-S group were significantly decreased (P<0.05),and the percentage of the cells at S phase was significantly increased (P<0.05 );the percentage of the cells at G2/M phase in MCF-7+8 Gy group was significantly increased (P<0.05 ), but there were no significant changes in MCF-7-S+ 8 Gy group. Conclusion Ionizing irradiation can cause the increasing of ROS level and apoptosis and G2/M phase arrest in breast cancer cells,but has no obvious effects on the breast cancer stem cells;it indicates that radio-resistance might be related to ROS level,apoptosis and G2/M phase arrest.

Objective To establish the MCF-7 cell models of Beclin 1 over-and low-expressions,and to detect the autophagic and apoptotic changes after 4 Gy irradiation,and to explore their molecular regulation mechanisms. Methods MCF-7,MCF-7 + 4Gy,MCF-7-Beclin 1 + 4Gy and MCF-7-Belcin 1 RNAi+ 4Gy groups were set up. Molecular biology method was used to construct Beclin 1 over-expression vector pcDNA3.1-Beclin 1,and to estabilish the Beclin 1 over- and low-expression cell models.After the cells were irradiated with 4 Gy, the autopahgic cell percentages were measured by fluorescence microscope with MDC staining, the apoptotic cell percentages were measured by FCM with AnnexinⅤ-FITC and PI staining,and the expressions of Beclin1,P53, Bcl-2 and Bax proteins were measured by Western blotting method.Results Compared with MCF-7 group,the autophagic and apoptotic cell percentages in MCF-7+4 Gy,MCF-7 Beclin 1 +4 Gy and MCF-7-Beclin 1 RNAi+4 Gy groups were significantly increased (P <0.05 or P <0.001 ),especially in MCF-7 Beclin 1+4 Gy group which was significantly higher than those in MCF-7 + 4 Gy (P < 0.05);while there was significant difference in the necrotic cell percentages between various groups. After 4 Gy irradiation, compared with MCF-7 group, the expression levels of Beclin 1,P53 and Bax proteins in MCF-7 + 4 Gy and MCF-7-Beclin 1 + 4 Gy groups were increased,but the expression levels of Bcl-2 protein were decreased,especially in MCF-7-Beclin 1 + 4 Gy group. Conclusion The MCF-7 cell models of Beclin 1 over-and low-expressions are successfully established,and ionizing radiation could induce the autophagy and apoptosis of MCF-7 cells,which is more obvious in Beclin 1 over-expression MCF-7 cells.Beclin 1 can activate P53,inhibit Bcl-2 and activate Bax,which forms the regulation of autophagy and apoptosis by P53 .