Hydroxytyrosol modulates the levels of microRNA-9 and its target sirtuin-1 thereby counteracting oxidative stress-induced chondrocyte death.

OBJECTIVE: Nutraceutical compounds, such as hydroxytyrosol (HT), have been found to exert protective effects in osteoarthritis (OA) by affecting a variety of key molecular and cellular processes in chondrocytes. However, to our knowledge, no relationship has been reported between nutraceuticals and microRNA (miR) network in OA models. Here, we identified a miR that is implicated in HT-mediated chondroprotection following oxidative stress condition by targeting sirtuin-1 (SIRT-1). METHODS: Human primary and C-28/I2 chondrocytes were pre-treated with 100 µM HT 30 min before 100 µM H2O2 addition. In silico analyses were exploited to select putative candidate miRs able to target SIRT-1 mRNA. Luciferase-based gene reporter assay was employed to demonstrate the direct link between miR-9 and its putative mRNA target. Transient transfection approach was performed to examine the effects of miR-9 levels on caspase activity, cell viability and expression of OA-related genes. RESULTS: MiR-9 was identified and confirmed as a post-transcriptional regulator of SIRT-1. MiR-9 and SIRT-1 levels showed opposite changes in chondrocytes following H2O2 and HT treatment. Moreover mir-9 silencing inhibited cell death induced by H2O2 partly through down-regulation of SIRT-1, whereas miR-9 overexpression markedly reduced the protective effect of HT. The manipulation of miR-9 levels also resulted in the modulation of OA-related gene expression, including MMP-13, VEGF and RUNX-2. CONCLUSIONS: These results show that miR-9 is a critical mediator of the deleterious and OA-related effects of oxidative stress in chondrocytes and that modulation of miR expression may be a crucial mechanism underlying the protective action of HT.

MicroRNA-155 suppresses autophagy in chondrocytes by modulating expression of autophagy proteins.

OBJECTIVE: Autophagy dysfunction has been reported in osteoarthritis (OA) cartilage. The objective of this study was to investigate the role of microRNA-155 (miR-155), which is overexpressed in OA, in the regulation of autophagy in human chondrocytes. DESIGN: Rapamycin (50 nM) and 2-deoxyglucose (2-DG) (5 mM) were used to stimulate autophagy in primary human articular chondrocytes and in the T/C28a2 human chondrocyte cell line. Cells were transfected with LNA GapmeR or mimic specific for miR-155 and autophagy flux was assessed by LC3 western blotting and by Cyto-ID(®) dye quantification in autophagic vacuoles. Expression of predicted miR-155 targets in the autophagy pathway were analyzed by real-time PCR and western blotting. RESULTS: Autophagy flux induced by rapamycin and 2-DG was significantly increased by miR-155 LNA, and significantly decreased after miR-155 mimic transfection in T/C28a2 cells and in human primary chondrocytes. These effects of miR-155 on autophagy were related to suppression of gene and protein expression of key autophagy regulators including Ulk1, FoxO3, Atg14, Atg5, Atg3, Gabarapl1, and Map1lc3. CONCLUSION: MiR-155 is an inhibitor of autophagy in chondrocytes and contributes to the autophagy defects in OA.

The provision of orthodontic services by general dental practitioners. 2. Factors influencing variation in service provision.

Previous work has shown that variations exist amongst general dental practitioners in the volume and type of orthodontic services provided, the type of orthodontic appliances used, and the objectives of the orthodontic treatment. The aims of this survey were to identify practitioner characteristics that account for variations in the level of orthodontic services provided and which distinguish providers and non-providers of orthodontic services. Multiple regression analysis revealed that four practitioner characteristics explained 41 per cent of the variance in the number of orthodontic patients treated. Dentists who treated more orthodontic patients: 1) treated more general practice patients; 2) frequently used multiple sources to keep up to date in orthodontics; 3) perceived their patient base to contain more children; and 4) were likely to have attended a Truitt course. Eleven variables best distinguished providers from non-providers of orthodontic treatment; 1, 2 and 3 above had the highest correlation with the discriminant function. The Null Hypothesis that selected characteristics of dentists providing orthodontic services were no different from those of dentists not providing orthodontic services was rejected. The provision of orthodontic services was associated with a higher level of continuing orthodontic education as well as treating more general practice patients, especially children.

The provision of orthodontic services by general dental practitioners. 1. Methods and descriptive results.

Information regarding orthodontic service provision by general dental practitioners in Australia is limited. The aim of this survey was to determine the amount and variety of orthodontic services provided by general dental practitioners in the Melbourne Statistical Division, Victoria, Australia. A random sample of 307 dentists drawn from the Victorian Dentists Register was surveyed by mailed questionnaire: 218 (71%) replied. Data were collected using a fortnight log. During this time 59 per cent of the dentists saw at least one orthodontic patient; one dentist saw 66 orthodontic patients. Removable orthodontic appliances were used by 35 per cent of the dentists and fixed orthodontic appliances by 18 per cent. Twenty-six per cent provided comprehensive orthodontic treatment, 22 per cent aligned incisors, and 21 per cent corrected anterior crossbites. The general dental practitioners surveyed provided a wide range of preventive and interceptive orthodontic services to generally a small percentage of their patients.