title: Comparison of gene expression of tissue inhibitor of matrix metalloproteinase-1 between continuous and intermittent distraction osteogenesis: a quantitative study on rabbits.
abstract: BACKGROUND
  Distraction osteogenesis is a controlled surgical procedure that initiates a regenerative process and uses mechanical strain to enhance the biological responses of the injured tissues to create new bone. To explore the effect of high-frequency mechanical traction on the expression of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), we compared the gene expression of TIMP-1 between continuous and intermittent distraction osteogenesis using a rabbit model of mandibular lengthening.
  
  
  METHODS
  Forty adult New Zealand white rabbits were randomly assigned to the intermittent and continuous distraction groups. A unilateral mandibular osteotomy was performed and a custom-designed manual-driven or auto-driven distractor was bridged over the osteotomy segments. Animals were sacrificed at day-6, day-10, day-14 and day-21 after osteotomy. Samples were examined with real-time polymerase chain reaction (PCR).
  
  
  RESULTS
  Real-time PCR examination showed significantly higher mRNA levels of TIMP-1 under continuous distraction than that under intermittent distraction at day-6 and day-10. No significant differences were found at day-14 and day-21.
  
  
  CONCLUSIONS
  High-frequency traction provides a good mechanical environment for accelerating bone formation by up-regulating TIMP-1.
authors.affiliation: Discipline of Oral Diagnosis and Polyclinics, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
authors.forename: Xi Ling
authors.initials: XL
authors.lastname: Liu
authors.forename: Lim Kwong
authors.initials: LK
authors.lastname: Cheung
authors.forename: Hua Xiang
authors.initials: HX
authors.lastname: Zhang
authors.forename: Jun Yuan
authors.initials: JY
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.forename: Li Wu
authors.initials: LW
authors.lastname: Zheng
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D008334:Mandible / Q000201:enzymology / Q000601:surgery; D063168:Mandibular Osteotomy / Q000379:methods; D061965:Matrix Metalloproteinase Inhibitors / Q000032:analysis*; D010012:Osteogenesis / Q000502:physiology; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods*; D011817:Rabbits; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction; D013314:Stress, Mechanical; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1