STIM2 regulates NMDA receptor endocytosis that is induced by short-term NMDA receptor overactivation in cortical neurons

Recent findings suggest an important role for the dysregulation of stromal interaction molecule (STIM) proteins, activators of store-operated Ca2+ channels, and the prolonged activation of N-methyl-D-aspartate receptors (NMDARs) in the development of neurodegenerative diseases. We previously demonstrated that STIM silencing increases Ca2+ influx through NMDAR and STIM-NMDAR2 complexes are present in neurons. However, the interplay between NMDAR subunits (GluN1, GluN2A, and GluN2B) and STIM1/STIM2 with regard to intracellular trafficking remains unknown. Here, we found that the activation of NMDAR endocytosis led to an increase in STIM2-GluN2A and STIM2-GluN2B interactions in primary cortical neurons. STIM1 appeared to migrate from synaptic to extrasynaptic sites. STIM2 silencing inhibited post-activation NMDAR translocation from the plasma membrane and synaptic spines and increased NMDAR currents. Our findings reveal a novel molecular mechanism by which STIM2 regulates NMDAR synaptic trafficking by promoting NMDAR endocytosis after receptor overactivation, which may suggest protection against excessive uncontrolled Ca2+ influx through NMDARs.

A randomized clinical trial comparing plaque removal efficacy of an oscillating-rotating power toothbrush to a manual toothbrush by multiple examiners

OBJECTIVE

To determine whether multiple examiners can demonstrate consistent plaque removal advantages for an oscillating-rotating power toothbrush versus a manual toothbrush.

METHODS

This was a replicate-use, single brushing, examiner-blind, randomized, two-treatment, four-period crossover clinical trial involving four examiners. Subjects were randomized to one of four treatment sequences involving two toothbrushes: an oscillating-rotating power toothbrush or a manual toothbrush. At each of the four visits, subjects arrived having abstained from oral hygiene for 24 h prior, and brushed with their assigned toothbrush and a marketed fluoride dentifrice under supervision unaided by a mirror. Plaque was assessed by each examiner using the Turesky-Modified Quigley-Hein Plaque Index at each study period before and after brushing. Data was analysed separately for each examiner using the analysis of covariance for crossover design.

RESULTS

Ninety-five subjects between the ages of 18 and 70 met the entrance criteria and were enrolled in the study. Eighty-seven subjects completed all four periods of the study. Both brushes delivered a significant plaque reduction when compared to baseline. Significant treatment differences were observed for all four examiners - ranging from 0.10 to 0.16 - in favor of the oscillating-rotating brush (P < 0.001). There were no adverse events reported or observed for either brush.

CONCLUSIONS

All four examiners demonstrated the power toothbrush removed significantly more plaque after a single brushing than the standard manual toothbrush. Both brushes were well tolerated.

A randomized 12-week clinical comparison of an oscillating-rotating toothbrush to a new sonic brush in the reduction of gingivitis and plaque

OBJECTIVE

To evaluate the efficacy of a marketed oscillating-rotating (O-R) power toothbrush (Oral-B Triumph with SmartGuide and FlossAction brush head, D34/EB25) to a new sonic toothbrush (Sonicare FlexCare Platinum) in the reduction of gingivitis and plaque over a 12-week test period.

METHODS

This was a single center, randomized, open label, examiner-blind, two-treatment, parallel group study. Subjects who met the entrance criteria were enrolled in the study and randomly assigned to either the O-R or sonic treatment group. Subjects brushed with their assigned toothbrush and a marketed fluoride dentifrice for two minutes twice daily at home for 12 weeks. Gingivitis and plaque were evaluated at Baseline, Week 6, and Week 12. Gingivitis was assessed using the Modified Gingival Index (MGI) and Gingival Bleeding Index (GBI), and plaque was assessed using the Rustogi Modified Navy Plaque Index (RMNPI). Data were analyzed using an Analysis of Covariance (ANCOVA) with Baseline as the covariate.

RESULTS

In total, 130 subjects (65 per group) were randomized to treatment and 127 subjects completed the study. Both brushes produced statistically significant (p < 0.001) reductions in gingivitis and plaque measures relative to Baseline. At Week 12, the O-R brush demonstrated significantly greater reductions than the sonic brush in whole mouth gingivitis measures (p = 0.007). Additionally, the O-R brush presented significantly fewer bleeding sites (p < 0.007) and significantly greater reductions in whole mouth plaque measures (p < or = 0.035) at Weeks 6 and 12 versus the sonic brush. The benefit for the O-R brush versus the sonic brush at Week 12 was 11.7% for gingivitis, 19.8% for number of bleeding sites, and 12.2% for whole mouth plaque. There were no adverse events reported or observed for either brush.

CONCLUSION

The oscillating-rotating toothbrush demonstrated statistically significantly greater reductions in whole mouth plaque at Weeks 6 and 12, as well as significantly greater gingivitis reductions over the long-term (12 weeks), compared to the new sonic toothbrush.

The plaque removal efficacy of a novel power brush head

OBJECTIVE

To assess the plaque removal efficacy of an oscillating/rotating power toothbrush with novel brush head (Oral-B Precision Clean) in comparison to an American Dental Association (ADA) reference manual toothbrush.

METHODS

This was a replicate-use, single-brushing, two-treatment, examiner-blind, randomized, four-period (visit) study with a crossover design. At each visit, subjects disclosed their plaque with disclosing solution for one minute, and an examiner performed a baseline (pre-brushing) plaque examination (Rustogi, et al. Modification of the Navy Plaque Index). Subjects were then instructed to brush for two minutes (according to manufacturer's instructions) with their assigned power toothbrush or as they normally do with the ADA manual brush under supervision, after which they again disclosed their plaque and were given a post-brushing plaque examination.

RESULTS

Both the power brush and manual brush showed statistically significant plaque reductions from baseline for the whole mouth, along the gingival margin, and on approximal surfaces. The power brush showed statistically significant advantages (p < 0.001) over the manual brush in plaque reduction for whole mouth (28.8%), gingival margin (44.3%), and approximal surfaces (20.7%).

CONCLUSION

The oscillating/rotating power toothbrush with a novel brush head showed statistically significantly superior plaque reduction (whole mouth, gingival margin, and approximal surfaces) compared to a manual toothbrush.

Comparison of a stabilized stannous fluoride/sodium hexametaphosphate dentifrice and a zinc citrate dentifrice on plaque formation measured by digital plaque imaging (DPIA) with white light illumination

OBJECTIVES

The objectives of this study were to verify use of a white light-illuminated adaptation of an established digital plaque image analysis (DPIA) technique to measure changes in plaque levels, and to compare the antiplaque efficacy of a 0.454% stannous fluoride/sodium hexametaphosphate dentifrice (SnF2/SHMP) and a 0.76% sodium monofluorophosphate/zinc citrate (ZnCit/SMFP) dentifrice using the white light DPIA system.

METHODS

White Light DPIA Qualification--17 subjects were enrolled in the study. The following four images were captured on different days: a) non-disclosed morning plaque; b) disclosed morning plaque; c)just-brushed plaque; and d) post-prophylaxis plaque levels. Comparative Dentifrice Assessment-Following the qualification study, 21 subjects were enrolled in the dentifrice assessment. During Phase I (two weeks acclimatization phase), subjects used a standardized oral hygiene regimen twice per day, consisting of a sodium fluoride dentifrice and a standard flat-profile manual toothbrush. In Phase II (two-week treatment phase), subjects were randomized to one of two treatment groups: SnF2/SHMP dentifrice (Crest Pro-Health) or the ZnCit/SMFP formulation (Viadent). During each phase, plaque levels were assessed in the morning prior to the morning tooth brushing (a.m.), post-brushing in the morning (p.b.), and in the afternoon (p.m.).

RESULTS

White Light DPIA Qualification--All 17 subjects completed the trial. The white light modification of DPIA successfully distinguished known variations in plaque coverage. Mean plaque coverage of the 12 anterior facial surfaces, as determined by the system for the four images, was: a) 0.07%; b) 11.44%; c) 4.99%; and d) 2.16%. Comparative Dentifrice Assessment-All 21 subjects completed the study. The SnF2/SHMP dentifrice provided a statistically significant 25% lower a.m. pre-brushing plaque level (p = 0.0385) versus ZnCit/SMFP. SnF2/SHMP also showed a directional 23% lower p.m. plaque (p = 0.09) level, and 15% less (p = 0.10) post-brushing plaque compared to ZnCit/SMFP.

CONCLUSION

The white light DPIA system was shown to be a sensitive method to measure changes in plaque levels. Using this system, a SnF2/SHMP dentifrice was found to be significantly more effective than a ZnCit/SMFP dentifrice in the prevention of overnight plaque growth.