This study investigated the relationship between occlusal contact and near contact areas defined by clenching intensity using electromyograms (EMGs) and mixing ability assessed with colour-changeable chewing gum. Participants comprised 44 dentate adults (24 men, 20 women) with a mean age of 28·2 ± 6·8 years. Silicone material was used to measure the occlusal contact and near contact areas (the area of each type of tooth, the total area of the first molar and second molar, the second premolar to the second molar and the first premolar to the second molar) defined by clenching intensity at 10% maximum voluntary contraction (MVC). Colour-changeable chewing gum was used to assess mixing ability. A colorimeter was used to measure colour changes, and the calculated colour difference (ΔE) was used as a measure of mixing ability. Correlation analysis of ΔE and occlusal contact and near contact areas revealed a significant positive correlation of 0·47 at 0-160 μm thicknesses of the silicone registration material of the second molar (P < 0·01). The near contact area with a thickness up to 200 μm was correlated with mixing ability, with the correlation strengthening as the interocclusal distance increased up to 160 μm. Notably, occlusal contact and near contact areas of the second molar were strongly correlated with mixing ability in dentate adults.

Background and PurposeThe chemokine receptor CXCR3 is implicated in a variety of clinically important diseases, notably rheumatoid arthritis and atherosclerosis. Consequently, antagonists of CXCR3 are of therapeutic interest. In this study, we set out to characterize binding sites of the specific low MW CXCR3 antagonist VUF10085 and the broad spectrum antagonist TAK-779 which blocks CXCR3 along with CCR2 and CCR5.Experimental ApproachMolecular modelling of CXCR3, followed by virtual ligand docking, highlighted several CXCR3 residues likely to contact either antagonist, notably a conserved aspartate in helix 2 (Asp-1122:63), which was postulated to interact with the quaternary nitrogen of TAK-779. Validation of modelling was carried out by site-directed mutagenesis of CXCR3, followed by assays of cell surface expression, ligand binding and receptor activation.Key ResultsMutation of Asn-1323.33, Phe-207 and Tyr-2716.51 within CXCR3 severely impaired both ligand binding and chemotactic responses, suggesting that these residues are critical for maintenance of a functional CXCR3 conformation. Contrary to our hypothesis, mutation of Asp-1122:63 had no observable effects on TAK-779 activity, but clearly decreased the antagonist potency of VUF 10085. Likewise, mutations of Phe-1313.32, Ile-2796.59 and Tyr-3087.43 were well tolerated and were critical for the antagonist activity of VUF 10085 but not for that of TAK-779.Conclusions and ImplicationsThis more detailed definition of a binding pocket within CXCR3 for low MW antagonists should facilitate the rational design of newer CXCR3 antagonists, with obvious clinical potential.