OBJECTIVETo compare the distribution and concentration of matrix metalloproteinases-2 (MMP-2) in different dentin depth of premolar and molar of young people.

METHODSFreshly extracted human premolars and molars (aged between 20-30) were sectioned to 1.5 mm thick slices along the longitudinal axis of the tooth separately. Enamel and pulp of each slice was removed, and then the premolar and molar slices were respectively divided into two subgroups according to superficial or deep dentin and pulverized to fine powder. After dentin protein was extracted, the concentrations of MMP-2 in different tooth were detected using fluorescent microsphere immunoassay.

RESULTSThe content of MMP-2 in superficial layer dentin of premolar was (0.022 ± 0.006) ng/mg. The content of MMP-2 in deep layer dentin of premolar was (2.087 ± 0.090) ng/mg. The content of MMP-2 in superficial layer dentin of molar was (0.336 ± 0.037) ng/mg. The content of MMP-2 in deep layer dentin of molar was (3.312 ± 0.308) ng/mg.

CONCLUSIONSMMP-2 exists in human coronal dentin. In the same type of teeth of young people, the concentration of MMP-2 in deep dentin was significant higher than those in superficial dentin. In the same dentin depth, the concentration of MMP-2 in molar was significant higher than those in premolar.

Adult ; Bicuspid ; Dental Enamel ; Dental Pulp ; Dentin ; chemistry ; Fluorescent Antibody Technique ; Humans ; Matrix Metalloproteinase 2 ; analysis ; Molar ; Tooth ; Tooth Crown ; Tooth Root ; Young Adult

Objective To investigate the effects and its possible mechanisms of tiopronin (TIP) on interleukin-2 (IL-2) immunotherapy of human leukemia KG-1 cells transplanted in nude mice.Methods KG-1 cells (1 x 107/ml) in logarithmic growth phase were injected subcutaneously into the groin of the left hind leg of the 45 5-week-old nude mice.When the subcutaneous tumor diameter was about 8 mm,nude mice were randomly divided into three groups (n =15):Control group (intraperitoneal injection of phosphate buffer),IL-2 group (hypodermic injection of IL-2),IL-2 + TIP group (hypodermic injection of IL-2 and intraperitoneal injection of TIP).The therapeutic effect of TIP combined with IL-2 on human leukemia KG-1 cells transplanted in nude mice was observed.The number of nature killer (NK) cells in peripheral blood of nude mice was detected by flow cytometry.Nitrate reductase assay was used to detect reactive nitric metabolite (RNM) levels in peripheral blood of nude mice.Enzyme linked immunosorbent assay (ELISA) was used to detect the levels of tumor necrosis factor-β (TNF-β) and interferon-γ (IFN-γ) in peripheral blood of nude mice.Terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) assay was used to analyze apoptosis.Results Both IL-2 and IL-2 + TIP could inhibit the growth of transplanted tumor.Compared with IL-2 group [(54.32 ± 4.32) ％],the tumor inhibition rate of IL-2 + TIP group was (90.15 ± 3.75)％,and its inhibition of tumor growth was more obvious (t =11.893,P ＜ 0.001).The tumor weights of Control group,IL-2 group and IL-2 + TIP group were (0.95 ± 0.05)g,(0.58 ± 0.03)g and (0.27 ± 0.07)g,and there was statistically significant difference among the three groups (F =52.716,P ＜ 0.001).Compared with IL-2 group,the tumor weight of IL-2 + TIP group was significantly reduced (P =0.008).The number of NK cells in IL-2 + TIP group was (0.658 ±0.157)/L,which was significantly higher than (0.452 ±0.124)/L of IL-2 group (P =0.021).The concentration of RNM in IL-2 + TIP group was (42.92 ± 4.68)μmol/ml,which was significantly lower than (163.38 ± 5.49)μmol/ml in IL-2 group (P =0.007).The concentrations of TNF-β and IFN-γin IL-2 + TIP group were (247.68 ± 8.24) pg/ml and (185.61 ±7.58) pg/ml,which were significantly higher than (97.48 ± 7.28)pg/ml (P =0.021) and (70.62 ± 8.47)pg/ml (P =0.015) in IL-2 group.The apoptotic rate of tumor cells in IL-2 + TIP group was (47.38±4.25)％,which was significantly higher than (21.41 ±2.79)％ in IL-2 group (P ＜0.001).Conclusion TIP can increase the sensitivity of leukemia cells to IL-2 immunothe-rapy by removing RNM,promoting NK cells activity and increasing NK cells-induced tumor cell apoptosis.

OBJECTIVETo systematically investigate the aging effect of thermocycling, water storage and bacteria aggression on the stability of resin-dentin bonds.

METHODSForty molars were sectioned perpendicularly to the axis of the teeth to expose the middle-coronal dentin surfaces. The dentin surfaces were then treated with Single Bond 2 and made a core build-up. According to random digits table, the bonding specimens were divided into four groups (n = 10) as follows: immediate control group, aging group with thermocycling for 5 000 times, aging group with artificial saliva storage for 6 months and aging group with bacteria aggression for 14 days. The specimens in each group were then subjected to microtensile bond strengths (µTBS) testing and nanoleakage evaluation respectively.

RESULTSAfter aging treatments, the three aging groups showed significantly lower µTBS than the immediate control group [(44.24 ± 12.75) MPa, P < 0.05]. The immediate control group also showed the lowest value of nanoleakage. The µTBS of aging group with bacteria aggression [(25.53 ± 7.39) MPa] was significantly lower than those of the other aging groups with artificial saliva storage[(29.72 ± 6.51) MPa] and thermocycling [(31.92 ± 11.87) MPa, P < 0.05]. There were no differences in the nanoleakage values among the three aging groups (P > 0.05).

CONCLUSIONSAll the aging treatments with artificial saliva storage, thermocycling and bacteria aggression could accelerate the degradation of bonding interfaces between an etch-and-rinse adhesive and dentin. Bacteria aggression showed the most impairing effect on the stability of resin-dentin bonds.

Adhesives ; Bisphenol A-Glycidyl Methacrylate ; Dental Bonding ; Dental Stress Analysis ; Dentin ; Dentin-Bonding Agents ; Humans ; Materials Testing ; Molar ; Resin Cements ; Saliva, Artificial ; Tensile Strength

Objective To investigate the effect of E1A gene on the radiosensitivity of human nasopharyngeal carcinoma cells and its possible mechanism. Methods The E1A gene was transfected into nasopharyngeal carcinoma CNE-2R cells by adenovirus vector. The expression of E1A gene was detected by RT-PCR. Untransfected CNE-2R cells(PBS group)and CNE-2R cells transfected with empty vector Ad-β-gal(Ad-β-gal group)and E1A(Ad-E1A group)were given 0 Gy,2 Gy,4 Gy,6 Gy,8 Gy 6 MV X-ray irradiation. The changes in radiosensitivity of CNE-2R cells were determined by colony-forming assay. Flow cytometry was used to analyze cell apoptosis in each group. The expression of NF-κB, CK2α, Bcl-2, and cleaved caspase-3 was measured by Western blot. Results RT-PCR confirmed that the E1A gene was transfected into CNE-2R cells and stably expressed. The Ad-E1A group had a significantly lower plating efficiency than the PBS group and the Ad-β-gal group(P<0.05). The Ad-E1A group had significantly lower cell survival rate at 2 Gy irradiation than the PBS group and the Ad-β-gal group(0.217 vs. 0.602, P<0.05;0.217 vs. 0.585, P<0.05). The Ad-E1A group had a significantly higher α/β value than the PBS group and the Ad-β-gal group(24.680 vs. 5.268, P<0.05;24.680 vs. 5.132, P<0.05). Flow cytometry results showed that irradiation alone could promote the apoptosis of CNE-2R cells,when combined with E1A gene,the apoptosis rate was significantly increased(P<0.05). Western blot results showed that E1A gene down-regulated the expression of NF-κB/p65,CK2α,and Bcl-2 and up-regulated the expression of cleaved caspase-3. Conclusions E1A gene can enhance the radiosensitivity of nasopharyngeal carcinoma cells by inhibiting the expression of CK2 to block the NF-κB signaling pathway and promoting cell apoptosis.

Objective To investigate the effect of Tiopronin (TIP) on interleukin (IL)-2 immunotherapy of human leukemia KG-1 cells and its possible mechanism.Methods KG-1 ceils in logarithmic growth phase were randomly divided into KG-1 + IL-2 group and KG-1 + IL-2 + TIP group.Methyl thiazolyl tetrazolium (MTI) assay and colony formation assay were used to detect the sensitivity and proliferation of KG-1 cells.The changes of reactive nitric metabolites (RNM) were detected with nitrate reductase method.The production of tumor necrosis factor (TNF)-3 and interferon (IFN)-γ,was detected with enzyme linked immunosorbent assay (ELISA).The expression of CD3ξ was detected with Western blot and real time polymerase chain reaction (RT-PCR).Results IL-2 and IL-2 + TIP could inhibit the growth of KG-1 cells.The inhibitory rate of KG-1 + IL-2 + TIP group was significantly higher than that of KG-1 + IL-2 group,and the sensitivity of KG-1 cells to IL-2 was 6.2 times higher.Both IL-2 and IL-2 + TIP group inhibited the colony formation of KG-1 cells.Compared to KG-1 + IL-2 group,KG-1 + IL-2 + TIP group inhibited the colony formation of KG-1 cells by 3.5 times.The RNM production of KG-1 + IL-2 group was (158.26 ± 3.82) μmol/ml,which was significantly higher than (45.18 ± 4.29) μ mol/ml of KG-1 + IL-2 + TIP group (P ＜ 0.05).The levels of TNF-β and IFN-γin KG-1 + IL-2 + TIP group were (253.28 ± 7.84) pg/ml and (181.25 ±6.41) pg/ml,which was significantly higher than (98.45 ±6.43) pg/ml and (68.74 ±8.26) pg/ml of KG-1 +IL-2 group (P＜0.05).The expression of CD3ξ in KG-1 +IL-2 +TIP group was significantly higher than that in KG-1 + IL-2 group.Conclusions Tiopronin can promote NK/T cell activity and increase the sensitivity of leukemia KG-1 cells to IL-2 by eliminating reactive nitrogen metabolites.