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Background: Natural head position (NHP), pharyngeal airway and maxillofacial growth pattern are correlated. The author's previous studies proved that following surgical correction of Skeletal Class II malocclusion, the over‐extended NHP returned upright, and the pharyngeal airway space (PAS) dimension expanded. Objective: The present study compares the post‐operative change in NHP and PAS after orthognathic surgery in Skeletal Class II and III malocclusion patients. Methods: Patients receiving orthognathic procedures to correct Skeletal Class II or III malocclusions were reviewed in this retrospective study. Pre‐operative and 6‐week post‐operative cone‐beam computed tomography datasets were collected. Variables representing the craniofacial pattern, the NHP and the PAS were measured three‐dimensionally. Post‐operative variables were compared with their pre‐operative counterparts using either repeat‐measure 2‐way analysis of variance or Wilcoxon matched‐pairs signed rank test. Results: Thirty cases of Skeletal Class II malocclusion and 13 cases of Skeletal Class III malocclusion were collected. Preoperatively, the inter‐group differences were significant in craniofacial pattern (68.14 ± 3.552 degree vs. 79.63 ± 2.497 degree, p <.0001) and the NHP (68.77 ± 11.02 degree vs. 82.83 ± 7.738 degree, p =.0002) while not significant in PAS; after surgery, the intergroup differences in craniofacial pattern and the NHP between groups decreased, and the PAS increased in both groups. Conclusion: Orthognathic surgery may improve compromised NHP and increase PAS in Skeletal Class II and III malocclusion patients. [ABSTRACT FROM AUTHOR]

Background and Purpose: The spider-venom peptide PcTx1 is the most potent and selective inhibitor of acid-sensing ion channel (ASIC) 1a. It has centrally acting analgesic activity and is neuroprotective in rodent models of ischaemic stroke. Understanding the molecular details of the PcTx1 : ASIC1a interaction should facilitate development of therapeutically useful ASIC1a modulators. Previously, we showed that several key pharmacophore residues of PcTx1 reside in a dynamic β-hairpin loop; conclusions confirmed by recent crystal structures of the complex formed between PcTx1 and chicken ASIC1 (cASIC1). Numerous peptide : channel contacts were observed in these crystal structures, but it remains unclear which of these are functionally important.Experimental Approach: We combined molecular dynamics (MD) simulations of the PcTx1 : cASIC1 complex with mutagenesis of PcTx1 and rat ASIC1a.Key Results: Crystal structures of the PcTx1 : cASIC1 complex indicated that 15 PcTx1 residues form a total of 57 pairwise intermolecular contacts (<5 Å) with 32 channel residues. MD simulations, however, suggested that about half of these interactions do not persist in solution. Mutation to alanine of only eight of 15 PcTx1 contact residues substantially altered ASIC1a inhibition by PcTx1. Our data reveal that many of the peptide-channel interactions observed in the PcTx1 : cASIC1 crystal structures are not important for PcTx1 inhibition of rat ASIC1a.Conclusions and Implications: We identified the atomic interactions that are critical for PcTx1 inhibition of ASIC1a. Our data highlight the value of combining structural information, MD and functional experiments to obtain detailed insight into the molecular basis of protein : protein interactions. [ABSTRACT FROM AUTHOR]