Protective effect of melatonin on bone marrow mesenchymal stem cells against hydrogen peroxide-induced apoptosis in vitro.

Bone marrow mesenchymal stem cells (MSCs) transplantation has shown great promises for treating various central nervous system (CNS) diseases. However, poor viability of transplanted MSCs in injured CNS has limited the therapeutic efficiency. Oxidative stress is one of major mechanisms underlying the pathogenesis of CNS diseases and has a negative impact on the survival of transplanted MSCs. Melatonin has recently been reported to have the antioxidant and anti-apoptotic properties in serial of cells. This study was designed to investigate the protective effect and potential mechanisms of melatonin against hydrogen peroxide (H2O2)-induced apoptosis of MSCs. MSCs were pretreated with melatonin (1, 10, and 100 nM, respectively) for 30 min, followed by exposure to 400 µM H2O2 and melatonin together for 12 h. The present study reports that melatonin pretreatment significantly attenuated H2O2-induced MSC apoptosis in a dose-dependent manner. Consistently, melatonin effectively suppressed the generation of intracellular ROS, expression ratio of Bax/Bcl-2, activation of caspase-3 and expression of phospho-P38MAPK in H2O2-induced MSCs. Luzindole, a nonselective melatonin receptor antagonist, significantly counteracted melatonin's promotion effect on cell survival, indicating that melatonin exerts its protective effect on MSCs, at least in part, through the activation of melatonin receptors. The findings suggest that melatonin may be an effectively protective agent against oxidative stress-induced MSC apoptosis.

[Effect of periodontal initial therapy together with Chinese herbal compound for clearing heat and detoxification on interleukin-1 beta and tumor necrosis factor-alpha in gingival crevicular fluid of patients with chronic periodontitis].

OBJECTIVE: To observe the effect of periodontal initial therapy together with Chinese herbal compound for clearing heat and detoxification (Abbr. TCM) on the levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) in gingival crevicular fluid (GCF) of patients with chronic periodontitis (CPD). METHODS: Thirty-four teeth of 24 patients with CPD were randomly assigned to the control group (17 teeth of 11 patients) and the treated group (17 teeth of 13 patients), they were treated for 8 weeks with periodontal initial therapy, but TCM was given additionally to the treated group. The GCF of the observed teeth was collected at the time before initial therapy (datum line) and at 2 and 8 weeks after treatment. At the same time, the clinical parameters, including probing depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP) were recorded, and the levels of TNF-alpha and IL-1 beta in GCF were measured by radioimmunoassay. RESULTS: The levels of TNF-alpha and IL-1 beta in GCF after treatment were significantly lowered in all patients as compared with those before treatment (P<0.01), while PD, CAL and BOP showed significant reduction (P<0.01). After treatment, TNF-alpha and IL-1 beta levels in the treated group were lower than those in the control group (TNF-alpha: 2.5551 +/- 1.0157 microg/L vs 3.4341 +/- 1.0762 microg/L, IL-1 beta: 0.1335 +/- 0.0216 microg/L vs 0.1471 +/- 0.0169 microg/L; P<0.05). CONCLUSION: TCM could enhance the effect of periodontal initial therapy in lowering TNF-alpha and IL-1 beta levels, which was attributed to reducing the inflammatory reaction of periodontal tissues.

[The experimental research of the influence of cervical settling method on marginal accuracy of wax patter].

OBJECTIVE: To study the influence of cervical settling method on marginal accuracy of wax patters. METHODS: 24 wax patterns were made on the standard cast specimens and round capsules of which twelve patters were made with the method of cervical settling (experiment group), twelve patters were made with the method of wax dripping (control group). Marginal accuracy of patterns were measured before sublation, sublation half an hour and twenty-four hours. RESULTS: The results revealed that marginal accuracy had significant difference between the cervical settling methods and wax dripping methods (P < 0.05). There was significant difference between the cervical settling methods measured after half an hour and twenty-four hours (P < 0.01). There was also significant difference between the wax dripping methods measured after half an hour and twenty-four hours (P < 0.01). CONCLUSION: Wax patterns with the method of cervical settling can improve marginal accuracy of patterns. The marginal accuracy of wax patters are influenced by the existing time.

[The test of metal-ceramic bonding strength among three ceramic alloies].

PURPOSE: To compare the metal-ceramic bonding strength of different ceramic alloies. METHODS: 30 wax sheets were divided into 6 groups at random. Each group included 5 sheets. After being invested conventionally with Bellaves SH,the samples were casted and fused with porcelain.The metal-ceramic bonding strength was evaluated. RESULTS: The highest bonding strength was found in Bio Herador N alloy, and then in TILITE alloy and Heraenium S alloy respectively. Bio Herador N alloy and TILITE alloy all had significant differences of the bonding strength before and after treatment (P<0.05). There was no significant differences in the bonding strength of the Heraenium S alloy after treatment (P>0.05). CONCLUSION: The bonding strength of precious metal-ceramic was higher than that of non-precious metal-ceramic.Pre-oxygen treatment can improve the metal-ceramic bonding strength of Bio Herador N alloy and TILITE alloy,but it had no effect on the metal-ceramic bonding strength of the Heraenium S alloy.