A methylation is one of the important approaches for regulation of gene expression. It plays a role in tumor development and progression and is closely associated with the radiosensitivity of cancer cells. The aberrant DNA methylation in cancer cells can provide biomarkers for early diagnosis of cancer. Moreover, it can contribute to the evaluation of the efficacy of radiotherapy, radiosensitivity enhancement, prognostic assessment, and disease monitoring. In order to provide a theoretical basis for further investigation of the epigenetic mechanisms for radioresistance of cancer cells, this paper reviews the relationship between DNA methylation and radiosensitivity and the potential value of DNA methylation in radiotherapy.

BACKGROUND:Acute toxicity in vivo experiments in previous studies has been confirmed that the median lethal dose of chitosan microcapsules is higher than 2 000 mg/kg, but the specific pathogenic mechanism is unclear.
OBJECTIVE:To explore the influence of nano chitosan on MC3T3-E1 cellgrowth as a bone substitute material, as wel as the physiological function of rats.
METHODS:MC3T3-E1 cells were respectively cultured in Dulbecco’s modified Eagle’s medium with different concentrations of chitosan nanoparticles (0, 10 mg/L, 100 mg/L, 1 g/L, 10 g/L). The absorbance values were determined. Changes in MC3T3-E1 cellmorphology were observed by scanning electron microscope after 24 hours culture. 10 g/L nano chitosan suspension was prepared using PBS. Two different doses of nano chitosan suspension (166.67 and 16.67 mg/kg body weight) with PBS were injected intraperitoneal y into Sprague-Dawley rats, three times a week, for 4 weeks. The control group was injected with equal volume of physiologic saline. Serum biochemical markers were detected to analyze the functions of liver and kidney of rats. Moreover, histopathology slices were observed to evaluate the morphological changes of tissue and inflammatory infiltration.
RESULTS AND CONCLUSION:10 mg/L, 100 mg/L, 1 g/L, 10 g/L nano chitosan suspensions were found growth inhibition in MC3T3-E1 cells as compared with the control group (P<0.05). The reunion of chitosan was observed in the cytoplasm of MC3T3-E1 cells by transmission electron microscopy. On the cellsurface, pseudopodia formed, wavy undulating membrane, nucleus degeneration, fragmentation and condensation were found. Compared with the control group, blood urea nitrogen, Na+levels were significantly increased in rats injected with nano chitosan suspension at two dosages, but the K+level in the high concentration group was decreased significantly (P<0.05). cellapoptosis was found in the liver and renal tissue in a dose-dependent manner. It suggests that apoptosis may be the possible mechanism of nano chitosan toxicity, and normal physiological function may be impacted over a certain dose.

Objective To examine the distribution and expression of dentin matrix protein1 ( DMP1 ) in the condylar cartilage and subchondral bone of osteoporosis rats. Methods Female Sprague-Dawley rats aged 6 months (n=30)wererandomlydividedinto3groups. TheShamgroupunderwentshamoperationonly(n=10),theOVX group ( n = 10 ) received a bilateral ovariectomy first and then saline solution treatment subcutaneously for 3 months. The RIS group ( n=10 ) also received a bilateral ovariectomy and then with risedronate treatment ( 2. 4μg/kg) subcutaneously for 3 months. Three months after the operation, the animals were sacrificed. Toluidine blue staining showed the structure changes of rat condylar cartilage region. The changes of osteoclasts in the bony subcondylar region were evaluated by tartrate-resistant acid phosphatase ( TRAP) staining. The expression of DMP1 was analyzed immunohistochemically and then performed by semi-quantitative imaging analyses. Results Toluidine blue staining showed a thickened hypertrophic layers of condylar cartilage in RIS group. The results of TRAP staining indicated that the number of osteoclasts was significantly greater in OVX group than RIS group (P<0. 05). Immunohistochemistry showed that DMP1 localized mainly in the chondrogenic layers and osteocytes, bony subcondylar region in three groups. The expression levels of DMP1 proteins statistically decreased in OVX group than the other two groups(both P<0. 05). Conclusion Bisphophonates may reduce the the number of osteoclasts in the condyle from osteoporosis rats, with increasing of the expression of DMP1, which may influences condylar cartilage biomineralization.

Objective To investigate the role of cancer stem cells in radiation resistance of esophageal cancer and its molecular mechanism, and to provide a theoretical basis for radiotherapy for esophageal cancer.Methods Esophageal cancer cell line TE1 was treated with 8 Gy of radiation. Esophageal cancer cell line with resistance to radiation, TE1-res, was established and screened.Cell counting was used to evaluate cell proliferation.Flow cytometry was used to determine the expression of CD44 (high) CD24(-) CD133(+) and apoptosis in cells.The colony formation assay was used to determine the colony-forming rate and cell survival curve.Bisulfite sequencing PCR was used to determine the methylation status of cancer suppressor genes.Comparison of the data was made by group t test or analysis of variance. Results Compared with TE1 cells, TE1-res cells had significantly enhanced proliferation, a significantly higher proportion of CD44( high) CD24(-) CD133(+) cells, and significantly enhanced resistance to apoptosis (mean value 20.84×105 vs.4.46×105/day, P=0.008;(38.0±2.9)%vs.(10.1±1.3)%, P=0.001;mean value 33.23% vs.10.50%, P=0.003 ) .After treatment with 8 Gy of radiation, TE1-res cells had significantly higher colony-forming rate and D0 value than TE1 cells ((14.3±2.6)%vs.(0.9±0.3)%, P=0.011;3.28 vs.2.19 Gy, P=0.125 ) .Moreover, the promoter methylation in cancer suppressor genes including SPINT2, CDKN1B, DKK1, TP53, and PPP2R1B was significantly enhanced in TE1-res cells than in TE1 cells ((89.7±4.9)%vs.(5.0±0.5)%, P=0.001;(92.3±4.7)%vs.(10.4±0.7)%, P=0.001;(90.7±3.7)%vs.(7.9±0.4)%, P=0.001;(83.4±5.7)%vs.(17.2±1.2)%, P=0.002;(90.2±
6.7)%vs.(4.4±1.2)%, P=0.002).Conclusions Cancer stem cells play an important role in radiation resistance of esophageal cancer. The resistance to radiation is closely associated with promoter hypermethylation in cancer suppressor genes including SPINT2, CDKN1B, DKK1, TP53, and PPP2R1B.

Objective To establish a radioresistant esophageal squamous cancer cell line,and to identify the radioresistant genes and mechanisms.Methods The radioresistant KYSE410-res cell line was established by repeated exposure of cell line KYSE410 to radiation.The proliferation and apoptosis of esophageal squamous cancer cells were evaluated before and after radiation.The changes in gene expression of the esophageal squamous cancer cells after radiation were determined by gene microarray and analyzed by group t test.The genes with significant difference in expression after radiation were validated.Results The KYSE410-res cells had significantly enhanced proliferation and anti-apoptosis than the KYSE410 cells (all P＜0.05).The result of gene microarray showed that compared with the KYSE410 cells,the KYSE410-res cells had the expression of 463 and 251 genes upregulated and downregulated by no less than 4 folds,respectively.Those genes with different expression levels after radiation were mainly responsible for cell proliferation,adhesion,signal transduction,angiogenesis,reactive oxygen metabolism,cell damage repair,and the MAPK/ERK signaling pathway.OAS2 and UBD were key proteins in the network.In the KYSE410-res cells,the expression of HLA-DQBI,MMP1,NCAM1,ZNF521,GPC6,SELENBP1,LCN15,and TFPI-2 genes measured by real-time PCR was consistent with that measured by gene microarray.Conclusions Abnormal activation of the MAPK/ERK signaling pathway,upregulated expression of OAS2 and UBD,downregulated expression of TFPI-2,and upregulated expression of MMPs may play a role in radioresistance of esophageal cancer cells.

RESULTS AND CONCLUSION:(1)The number of apoptotic cels in rat condylar cartilage and subcondylar region: the sham operation group < the treatment group < the model group (alP< 0.05). (2)Expression of Bcl-2: The trend of the model group was lower than that in the sham operation group, although there was no statisticaly significant difference between the two groups; Bcl-2 expression in the treatment group was statisticaly higher compared to the model group (P< 0.05).(3)Expression of Bax and Caspase-3: The expression levels of Bax and Caspase-3 were higher in the model group than in the sham operation group (alP< 0.05), while Bax and Caspase-3 expression was lower in the treatment group than that in the model group (alP< 0.05). The results suggested that bisphophonates can regulate apoptosis in condylar cartilage from osteoporosis rats by changing the expression of Bcl-2, Bax and Caspase-3.

Objective To investigate effect of high glucose on the function of endothelial and the underlying mechanisms in human umbilical vascular endothelial cells (HUVECs).Methods The experiment was divided into 4 groups: normal group (NG), low dose group (LG), middle dose group (MG) and high dose group ( HG) .The concentration of glucose in the culture medium was 5.5, 10, 20, 30 mmol/L in the 4 groups, respectively.The HUVECs was cultured for 0, 24, 48 h.At different time point, the cell viability were measured by MTT.The secretary content of nitric oxide (NO) in the supernatant were detected using test kit.The extraction of protein were extracted for Western blot analysis to detect the expression of endothelial nitric oxide synthase (eNOS).ResuIts Compared with normal group at same time point (cultured for 24 h), the cell viability and the content of NO were significantly decreased in LG, MG(P<0.05).The expression of eNOS in HG were markedly reduced (P<0.01).Compared with normal group at same time point (cultured for 48 h), the cell viability decreased significantly in HG (P <0.05).The expression of eNOS were markedly decreased 11.91, 25.72 and 34.50% in LG, MG and HG, respectively.A rising trend of cell viability were found in NG, LG and MG, but a descending trend were found in HG within 48 h.ConcIusion The cell viability were significantly affected by high glucose.The endothelial dysfunction induced by high glucose may be associated with the reduction of eNOS and NO production.

A new method was developed for the determination of 11 fat_soluble vitamins ( A, D, E and K) and its derivatives in vitamin tablets by ultra performance convergence chromatography ( UPC2 ) . The mobile phase was the mixture of supercritical CO2 and acetonitrile at a flow rate of 1 mL/min. The separation was carried out on the Waters Acquity UPC2 HSS C18 SB 100 mm × 3. 0 mm i. d. , 1. 8 μm column. The UV detector was set at a wavelength of 284 nm. The limits of detection ( LOD) were 1. 5-2. 0 mg/L, and the calibration linear for VK1 , VK2 , VK3 and VB3 was 3-300 mg/L, linear for VA, VA palmitate, VA formic acid, VE, VE acetate, VD2 and VD3 was 5-300 mg/L, respectively. Its spiked recoveries were 97. 31%-98. 76%, and the relative standard deviations ( RSDs) were 0. 41%-0. 96%. The method is applicable for the determination of fat_soluble vitamins ( A, D, E and K) and Their derivatives in vitamin tablets.

BACKGROUND: Diabetes mel itus is one of the most common systemic diseases, which often leads to the changes of the jaw and other bone structure, as wel as the abnormal changes of mineral metabolism. OBJECTIVE: To observe the three-dimensional structure and histopathological changes of the mandible in type 1 diabetes mel itus mice. METHODS: The mice were randomly divided into control group and diabetes mel itus group. The diabetes mel itus group received intraperitoneal injection of 50 mg/kg streptozotocin for 5 days to establish a type 1 diabetes mel itus model, and the control group received intraperitoneal injection of citrate buffer. RESULTS AND CONCLUSION: At 3 weeks after modeling, the micro-CT technique was used to observe the three-dimensional structure of the mandibles in the two groups. The quantitative analysis on the microstructure of cancel ous bone and cortical bone showed that the bone mineral density, bone volume fraction, trabecular number and trabecular thickness of cancel ous bone in the interest region in the mandible of type 1 diabetes mel itus mice were significantly decreased when compared with that in the control group (P < 0.01, P < 0.05), while the structure model index was increased significantly (P < 0.05); the mineral density and area of cortical bone were decreased in the diabetes mel itus group (P < 0.05). Hematoxylin-eosin staining showed that the number and volume of mandibular trabeculae of type 1 diabetes mel itus mice were decreased. The results suggest that the three-dimensional structure of the cancel ous bone and cortical bone in the streptozotocin-induced type 1 diabetes mel itus mice are changed significantly, and the microstructure change of the cancel ous bone is more obvious.

BACKGROUND:Insulin-like growth factor 1 is the key factor during cartilage development, which is involved in the growth and reconstruction of condylar cartilage.
OBJECTIVE:To study the effect of insulin-like growth factor 1 on cel apoptosis and the apopotosis-associated factors of Bcl-2, Bax mRNA and protein expressions of rat condylar chondrocytes.
METHODS:The 1-day-old and 28-day-old rat condylar chondrocytes were cultured and identified in vitro. The condylar chondrocytes with different ages were divided into experimental group and control group. After being starved for 24 hours, chondrocytes in the experimental group were incubated with 100μg/L recombined rat insulin-like growth factor 1 for 48 hours, while the chondrocytes in the control group were incubated normal y. RESULTS AND CONCLUSION:Compared with the control group, after being incubated with recombined
insulin-like growth factor 1, the number of condylar chondrocytes was increased with high speed proliferation (P<0.05). Real-time RCR and western blot analysis revealed that the expression levels of Bcl-2 mRNA and protein were increased after added with recombined rat insulin-like growth factor 1, while the expression levels of Bax and protein were decreased (P<0.05). The results indicate that insulin-like growth factor 1 can promote the
proliferation and reduce cel apoptosis of newborn and adolescent rat condylar chondrocytes, which may be mediated by Bcl-2 and Bax.