title: Effect of cleft palate repair on the susceptibility to contraction-induced injury of single permeabilized muscle fibers from congenitally-clefted goat palates.
abstract: OBJECTIVE
  Despite cleft palate repair, velopharyngeal competence is not achieved in approximately 15% of patients, often necessitating secondary surgical correction. Velopharyngeal competence postrepair may require the conversion of levator veli palatini muscle fibers from injury-susceptible type 2 fibers to injury-resistant type 1 fibers. As an initial step to determining the validity of this theory, we tested the hypothesis that, in most cases, repair induces the transformation to type 1 fibers, thus diminishing susceptibility to injury.
  
  
  METHODS
  Single permeabilized levator veli palatini muscle fibers were obtained from normal palates and nonrepaired congenitally-clefted palates of young (2 months old) and adult (14 to 15 months old) goats and from repaired palates of adult goats (8 months old). Repair was done at 2 months of age using a modified von Langenbeck technique.
  
  
  METHODS
  Fiber type was determined by contractile properties and susceptibility to injury was assessed by force deficit, the decrease in maximum force following a lengthening contraction protocol expressed as a percentage of initial force.
  
  
  RESULTS
  For normal palates and cleft palates of young goats, the majority of the fibers were type 2 with force deficits of approximately 40%. Following repair, 80% of the fibers were type 1 with force deficits of 20% +/- 2%; these deficits were 45% of those for nonrepaired cleft palates of adult goats (p < .0001).
  
  
  CONCLUSIONS
  The decrease in the percentage of type 2 fibers and susceptibility to injury may be important for the development of a functional levator veli palatini muscle postrepair.
authors.affiliation: Department of Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Rader
authors.forename: Paul S
authors.initials: PS
authors.lastname: Cederna
authors.forename: William T
authors.initials: WT
authors.lastname: McClellan
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Caterson
authors.forename: Kip E
authors.initials: KE
authors.lastname: Panter
authors.forename: Deborah
authors.initials: D
authors.lastname: Yu
authors.forename: Steven R
authors.initials: SR
authors.lastname: Buchman
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Larkin
authors.forename: John A
authors.initials: JA
authors.lastname: Faulkner
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Weinzweig
mesh_terms: D000367:Age Factors; D000818:Animals; D001696:Biomechanical Phenomena; D002972:Cleft Palate / Q000473:pathology / Q000601:surgery*; D004195:Disease Models, Animal; D006041:Goats; D009119:Muscle Contraction / Q000502:physiology; D024510:Muscle Development / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000473:pathology* / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000473:pathology* / Q000502:physiology; D010156:Palatal Muscles / Q000254:growth & development / Q000473:pathology*; D010159:Palate / Q000473:pathology; D021362:Palate, Hard / Q000601:surgery; D010160:Palate, Soft / Q000601:surgery; D012518:Sarcomeres / Q000473:pathology / Q000502:physiology; D013314:Stress, Mechanical; D013997:Time Factors