title: Raised intensity phonation compromises vocal fold epithelial barrier integrity.
abstract: OBJECTIVE
  We investigated the hypothesis that 30 minutes of raised intensity phonation alters transcript levels of vocal fold intercellular tight junction proteins and disrupts the vocal fold epithelial barrier.
  
  
  METHODS
  Prospective animal study.
  
  
  METHODS
  Eighteen New Zealand white breeder rabbits were randomly assigned to receive 30 minutes of raised intensity phonation or approximation of the vocal folds without phonation. Quantitative polymerase chain reaction (qPCR) was used to investigate transcript levels of the epithelial intercellular tight junction proteins, occludin and zonula occludin-1 (ZO-1), and the adherens junction proteins β-catenin and E-cadherin. Structural alterations to the vocal fold epithelium were further examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
  
  
  RESULTS
  Mann-Whitney U revealed significantly decreased occludin (P = .016) and β-catenin (P = .016) gene expression from rabbits undergoing raised intensity phonation compared with control. There were no significant differences in Z0-1 and E-cadherin gene expression between groups (P > .025). SEM revealed significant obliteration, desquamation, and evidence of microhole formation in rabbit vocal folds exposed to raised intensity phonation compared with control, whereas TEM revealed dilated intercellular morphology between groups.
  
  
  CONCLUSIONS
  Results provide support for the hypothesis that a transient episode of raised intensity phonation alters transcript levels of vocal fold intercellular tight junction proteins and disrupts integrity of the epithelial barrier. The loss of barrier integrity may have significant consequences on epithelial defenses and compromise protection of the underlying mucosa from damage secondary to prolonged vibration exposure.
authors.affiliation: Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee 37232-4480, USA. bernard.rousseau@vanderbilt.edu
authors.forename: Bernard
authors.initials: B
authors.lastname: Rousseau
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suehiro
authors.forename: Nicholas
authors.initials: N
authors.lastname: Echemendia
authors.forename: Mahalakshmi
authors.initials: M
authors.lastname: Sivasankar
mesh_terms: D000818:Animals; D015820:Cadherins / Q000032:analysis; D004848:Epithelium / Q000502:physiology / Q000648:ultrastructure; D015870:Gene Expression; D008565:Membrane Proteins / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D062793:Occludin; D010699:Phonation / Q000502:physiology*; D010750:Phosphoproteins / Q000032:analysis; D016133:Polymerase Chain Reaction; D011817:Rabbits; D019108:Tight Junctions / Q000502:physiology; D014732:Vibration; D014827:Vocal Cords / Q000502:physiology*; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin / Q000032:analysis
chemical_list: D015820:Cadherins; D008565:Membrane Proteins; D062793:Occludin; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin