[Comparison of the clinical value of three reciprocating single nickel-titanium instruments in preparation of simulated curved root canals].

PURPOSE: To explore the application value of three reciprocating single nickel-titanium instruments in preparation of simulated curved root canals. METHODS: One hundred and fifteen single-curved resin simulation root canals were selected and divided into Reciproc group (group A, 28), One file group (group B, 29), Wave One group (group C, 29) and control group (group D, 29) by random graph method. The simulated root canals were prepared according to the specifications of the instructions, root canal preparation, resin removal, root canal cleaning effect, center positioning ability and root canal width were compared. SPSS 22.0 software package was used for statistical analysis. RESULTS: There was no significant difference in quality and curvature among four groups(P＞0.05). The difference in root canal preparation time among the four groups was statistically significant (P＜0.05), and the root canal preparation time in group B was the shortest(P＜0.05). Comparison of resin removal at the root canal orifice and the midpoint of the bending start point among four groups, the difference was statistically significant(P＜0.05). The root canal wall debris scores and smear layer scores in four groups were significantly different(P＜0.05). Compared with group A, B and D, the root canal wall debris scores of the crown, middle and tip of group C were the lowest, the scores of smear layer on the crown and middle of the root canal wall was the lowest(P＜0.05). There was no significant difference in the center positioning ability of the four groups at 5 mm, 6 mm and 7 mm from the apical foramen(P＞0.05). There was no significant difference in root canal width among four groups (P＞0.05). CONCLUSIONS: Reciproc, One file and Wave One reciprocating single nickel-titanium instruments can maintain the original shape of the simulated root canal. Compared with Reciproc and Wave One, One file has better root canal shaping ability and cleaning effect.

[Temporal expression of PD-1 and PD-L1 during the development of experimental periodontitis in rats and its implications].

PURPOSE: To study the temporal expression of programmed death receptor 1 (PD-1) and its ligand (PD-L1) in the development of periodontitis in rats. METHODS: SD rats were randomly divided into control group and model group, and 4 subgroups were divided in each model group according to the time of measurement: group A (1 week), group B (2 weeks), group C (3 weeks) and group D (4 weeks). There were 8 rats in each subgroup. Maxillary periodontitis models were made by using "thread ligation + vaccination LPS-PG" in rats. Periodontal tissue specimens were examined and bone resorption areas were determined in each group. Tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1ß), interleukin 6 (IL-6) and transforming growth factor beta (TGF-ß) mRNA in periodontal tissue in each group were determined by RT-PCR method. PD-1 and PD-L1 protein expression in periodontal tissues in each group were determined by Western blotting. The data were analyzed by SPSS 22.0 software package. RESULTS: During modeling period, amelocemental junction-alveolar crest(ACJ-AC) distance and bone resorption area of the first molar in model group gradually increased (P<0.05), which were significantly different from the control group at the corresponding time point (P<0.01). During modeling period, TNF-α, IL-1ß and IL-6 mRNA level in periodontal tissues in the model group was continuously increased(P<0.05), and TGF-ß mRNA was continuously decreased(P<0.05), which was significantly different from the control group at the corresponding time point(P<0.01). During disease progress, PD-1 and PD-L1 protein level in periodontal tissues in each model group was continuously increased(P<0.05), which was significantly different from the control group at the corresponding time point (P<0.01); and PD-1 and PD-L1 protein levels in periodontal tissues in each model group was positively correlated to TNF-α and IL-6 mRNA levels(P<0.01). CONCLUSIONS: PD-1, as an immunosuppressive molecule and its receptor PD-L1, can promote the progression of periodontal inflammation, and its effect may be achieved by regulating the expression of TNF-α and IL-6.Regulating the expression of PD-1 and PD-L1 may be a new target for the treatment of periodontitis.

Ultrasound-targeted transfection of tissue-type plasminogen activator gene carried by albumin nanoparticles to dog myocardium to prevent thrombosis after heart mechanical valve replacement.

BACKGROUND: There are more than 300,000 prosthetic heart valve replacements each year worldwide. These patients are faced with a higher risk of thromboembolic events after heart valve surgery and long-term or even life-long anticoagulative and antiplatelet therapies are necessary. Some severe complications such as hemorrhaging or rebound thrombosis can occur when the therapy ceases. Tissue-type plasminogen activator (t-PA) is a thrombolytic agent. One of the best strategies is gene therapy, which offers a local high expression of t-PA over a prolonged time period to avoid both systemic hemorrhaging and local rebound thrombosis. There are some issues with t-PA that need to be addressed: currently, there is no up-to-date report on how the t-PA gene targets the heart in vivo and the gene vector for t-PA needs to be determined. AIMS: To fabricate an albumin nano-t-PA gene ultrasound-targeted agent and investigate its targeting effect on prevention of thrombosis after heart mechanic valve replacement under therapeutic ultrasound. METHODS: A dog model of mechanical tricuspid valve replacement was constructed. A highly expressive t-PA gene plasmid was constructed and packaged by nanoparticles prepared with bovine serum albumin. This nanopackaged t-PA gene plasmid was further cross-linked to ultrasonic microbubbles prepared with sucrose and bovine serum albumin to form the ultrasonic-targeted agent for t-PA gene transfection. The agent was given intravenously followed by a therapeutic ultrasound treatment (1 MHz, 1.5 w/cm(2), 10 minutes) of the heart soon after valve replacement had been performed. The expression of t-PA in myocardium was detected with multiclonal antibodies to t-PA by the indirect immunohistochemical method. Venous blood t-PA and D-dimer contents were tested before and 1, 2, 4, and 8 weeks after the operation. RESULTS: The high expression of t-PA could be seen in myocardium with increases in blood t-PA and D-dimer contents and thrombosis was prevented 8 weeks after operation. CONCLUSION: We successfully fabricated an albumin nano-t-PA gene ultrasound-targeted agent that could prevent dog thrombosis after mechanical heart valve replacement. Our study provides an experimental basis for prevention of human thrombosis-related diseases.