The Radiopacity and Antimicrobial Properties of Different Radiopaque Double Antibiotic Pastes Used in Regenerative Endodontics.

INTRODUCTION: We evaluated the radiopacity and antibacterial properties of various concentrations of double antibiotic paste (DAP) containing barium sulfate (BaSO4) or zirconium oxide (ZrO2) radiopaque agents. METHODS: The radiopacity of 1, 10, and 25 mg/mL DAP containing 30% (w/v) BaSO4 or ZrO2, DAP-free radiopaque pastes, and commercially available radiopaque calcium hydroxide (Ca[OH]2) were evaluated according to ISO 6876/2001 with slight modifications (n = 6 per group). Dentin samples (n = 70) infected anaerobically for 3 weeks with bacterial biofilms obtained from a root canal of an immature tooth with pulpal necrosis were treated with similar experimental pastes or received no treatment (n = 7). After 1 week, the pastes were rinsed off, and biofilm disruption assays were conducted. To show the residual antibacterial effects, sterile dentin samples (n = 70) were pretreated for 1 week with the same pastes (n = 7). The pastes were rinsed off, and the samples were immersed in phosphate-buffered saline for 24 hours and infected anaerobically with the same bacterial biofilm mentioned earlier for 3 weeks before conducting biofilm disruption assays. Sterile dentin blocks were used in both antibacterial analyses as negative control groups (n = 7). Wilcoxon rank sum tests were used for statistical analyses. RESULTS: No tested concentrations of BaSO4 DAP or ZrO2 DAP showed significant differences from Ca(OH)2 in radiopacity. However, all tested concentrations of BaSO4 DAP, ZrO2 DAP, and Ca(OH)2 exhibited significant direct antibacterial effects. ZrO2 DAP at 1 mg/mL and Ca(OH)2 did not show significant residual antibacterial effects. CONCLUSIONS: BaSO4 DAP at 1 mg/mL provided significantly superior residual antibacterial effects and comparable radiopacity with the commercially available Ca(OH)2.

Direct and indirect antibacterial effects of various concentrations of triple antibiotic pastes loaded in a methylcellulose system.

We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin blocks (n = 60) and treated with clinically used TAP (1,000 mg/mL), low concentrations of methylcellulose-based TAP (100, 10, and 1 mg/mL), placebo paste, or 1.5% NaOCl (n = 10). The pastes were then removed, and biofilm disruption assays were performed. Additional dentin blocks (n = 120) were pretreated with the same experimental groups (n = 20). The pastes were rinsed off, and the samples were immersed independently in phosphate-buffered saline for 2 and 4 weeks (n = 10). E.faecalis was then grown on the dentin blocks, and biofilm disruption assays were performed. Fisher's Exact and Wilcoxon rank sum tests were used for statistical analyses. With regard to direct antibacterial effects, all treatment groups demonstrated complete eradication of biofilms in comparison to placebo paste, while 10 mg/mL of TAP or higher provided substantial residual antibacterial effects. However, dentin treated with 1 mg/mL of TAP or 1.5% NaOCl did not provide substantial residual antibacterial effects. Dentin pretreated with 10 mg/mL of TAP or higher exhibited extended residual antibacterial effects and can thus be used during endodontic regeneration.(J Oral Sci 58, 575-582, 2016).

Aire-dependent thymic development of tumor-associated regulatory T cells.

Despite considerable interest in the modulation of tumor-associated Foxp3(+) regulatory T cells (T(regs)) for therapeutic benefit, little is known about the developmental origins of these cells and the nature of the antigens that they recognize. We identified an endogenous population of antigen-specific T(regs) (termed MJ23 T(regs)) found recurrently enriched in the tumors of mice with oncogene-driven prostate cancer. MJ23 T(regs) were not reactive to a tumor-specific antigen but instead recognized a prostate-associated antigen that was present in tumor-free mice. MJ23 T(regs) underwent autoimmune regulator (Aire)-dependent thymic development in both male and female mice. Thus, Aire-mediated expression of peripheral tissue antigens drives the thymic development of a subset of organ-specific T(regs), which are likely coopted by tumors developing within the associated organ.

Abnormal burst patterns of single neurons recorded in the substantia nigra reticulata of behaving 140 CAG Huntington's disease mice.

Huntington's disease (HD) is an inherited neurodegenerative disorder that causes neurological pathology in the basal ganglia and related circuitry. A key site of HD pathology is striatum, the principal basal ganglia input structure; striatal pathology likely changes basal ganglia output but no existing studies address this issue. In this report, we characterize single-neuron activity in the substantia nigra reticulata (SNr) of awake, freely behaving 140 CAG knock-in (KI) mice at 16-40 weeks. KI mice are a well characterized model of adult HD and are mildly symptomatic in this age range. As the primary basal ganglia output nucleus in rodents, the SNr receives direct innervation from striatum, as well as indirect influence via polysynaptic inputs. We analyzed 32 single neurons recorded from KI animals and 44 from wild-type (WT) controls. We found increased burst rates, without a concordant change in spike discharge rate, in KI animals relative to WTs. Furthermore, although metrics of burst structure, such as the inter-spike interval in bursts, do not differ between groups, burst rate increases with age in KI, but not WT, animals. Our findings suggest that altered basal ganglia output is a physiological feature of early HD pathology.