Light-Induced Opening of the TRP Channel in Isolated Membrane Patches Excised from Photosensitive Microvilli from Drosophila Photoreceptors.

Drosophila phototransduction occurs in light-sensitive microvilli arranged in a longitudinal structure of the photoreceptor, termed the rhabdomere. Rhodopsin (Rh), isomerized by light, couples to G-protein, which activates phospholipase C (PLC), which in turn cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) generating diacylglycerol (DAG), inositol trisphosphate and H+. This pathway opens the light-dependent channels, transient receptor potential (TRP) and transient receptor potential like (TRPL). PLC and TRP are held together in a protein assembly by the scaffold protein INAD. We report that the channels can be photoactivated in on-cell rhabdomeric patches and in excised patches by DAG. In excised patches, addition of PLC-activator, m-3M3FBS, or G-protein-activator, GTP-γ-S, opened TRP. These reagents were ineffective in PLC-mutant norpA and in the presence of PLC inhibitor U17322. However, DAG activated TRP even when PLC was pharmacologically or mutationally suppressed. These observations indicate that PLC, G-protein, and TRP were retained functional in these patches. DAG also activated TRP in the protein kinase C (PKC) mutant, inaC, excluding the possibility that PKC could mediate DAG-dependent TRP activation. Labeling diacylglycerol kinase (DGK) by fusion of fluorescent mCherry (mCherry-DGK) indicates that DGK, which returns DAG to dark levels, is highly expressed in the microvilli. In excised patches, TRP channels could be light-activated in the presence of GTP, which is required for G-protein activation. The evidence indicates that the proteins necessary for phototransduction are retained functionally after excision and that DAG is necessary and sufficient for TRP opening. This work opens up unique possibilities for studying, in sub-microscopic native membrane patches, the ubiquitous phosphoinositide signaling pathway and its regulatory mechanisms in unprecedented detail.

Enamel fracture in the primary dentition has no impact on children's quality of life: implications for clinicians and researchers.

AIM: The aim of this study was to quantify the impact of traumatic dental injuries (TDI) on oral-health-related quality of life (OHRQoL) of preschool children, when enamel fractures were either included or excluded within the category of TDI. MATERIAL AND METHODS: An oral health survey was undertaken of preschool children, age 1-5 years attending public nurseries in Canoas, Brazil. Children were examined for TDI, dental caries, and malocclusion. Parents were interviewed on their perception of their child's OHRQoL (Early Childhood Oral Health Impact Scale-ECOHIS) and their sociodemographic background. Multivariable Poisson regression models with robust variance were fitted to assess the impacts of TDI (including and excluding enamel fractures) on OHRQoL. RESULTS: A full dataset was collected from 76% of the eligible population. The prevalence of TDI was 13.4% (171/1275). The prevalence of any impact (ECOHIS ≥ 1) was significantly higher in children with crown discoloration (29.7%), enamel/dentin fracture (29.2%), and avulsion (73.3%), compared to children with enamel fracture (16.2%) or without a TDI (15.8%) (P < 0.001). Enamel fractures were the most prevalent TDI (40%) but halved the proportion of children with a reported impact from their TDI. The mean increase in OHRQoL impact for those children with a TDI was 1.59 (95%CI 1.20-2.10) when enamel fracture was included, and 1.86 (95%CI 1.39-2.50) when it was excluded. CONCLUSION: Enamel fractures have no significant impact on young children's quality of life. Including enamel fractures within the diagnosis of TDI increases the prevalence of TDI while reducing the OHRQoL impact of TDI for the primary dentition.

Interventions for treating traumatised permanent front teeth: luxated (dislodged) teeth.

BACKGROUND: Dental trauma is common especially in children and young adults. One group of dento-alveolar injuries is classified as luxation. This group includes a subgroup of severe injuries where the tooth is displaced from its original position. These injuries are classified further by the direction in which the tooth has been displaced, namely: intrusion, extrusion and lateral luxation. OBJECTIVES: To evaluate the effects of a range of interventions for treating displaced luxated permanent front teeth. SEARCH METHODS: Search strategies were developed for MEDLINE via OVID and revised appropriately for the following databases: Cochrane Oral Health Group's Trials Register (to 20 August 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 8), MEDLINE via OVID (1966 to August 2012), EMBASE via Elsevier (1974 to August 2012), and LILACS via BIREME (1982 to August 2012). Dissertations, Theses and Abstracts were searched as were reference lists from articles. There were no language restrictions. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials of treatment interventions for displaced luxated permanent front teeth. Included trials had to have a minimum follow-up period of 12 months. DATA COLLECTION AND ANALYSIS: Two review authors independently and in duplicate assessed the eligibility of all reports identified in the searches. Authors were contacted for additional information where required. MAIN RESULTS: No randomised or quasi-randomised controlled trials were found. AUTHORS' CONCLUSIONS: We found no randomised or quasi-randomised trials of interventions to treat displaced luxated permanent front teeth. Current clinical guidelines are based on available information from case series studies and expert opinions. Randomised controlled trials in this area of dental trauma are required to robustly identify the benefits of different treatment strategies.