title: [Experimental study on the impact of photodynamic therapy on the normal vocal cord injury].
abstract: OBJECTIVE
  To investigate the reactive characteristics of normal vocal cord tissues to photodynamic therapy (PDT) and the damage effects of different concentration of photosensitizer and different light on normal rabbit vocal cord. Making the preliminary research of PDT in clinical treatment of chronic inflammation of the vocal cords and precancerous lesions.
  
  
  METHODS
  Twenty-five healthy Japanese big ear experimental rabbits were randomly divided into 5 groups: low work rate low dose group A (100 mW, 10%5-ALA), high work rate low dose group B (200 mW, 10%5-ALA), high work rate high dose group C (200 mW, 20%5-ALA), low work rate high dose group D (100 mW, 20%5-ALA) and normal control group E. The issue damage and wound recovery were observed in 1 d, 3 d, 7 d, 14 d, 28 d after intervention.
  
  
  RESULTS
  A severe inflammation reaction was observed in group A, B, C, D after intervened with PDT compared to normal group. The reaction of group A was lighter, and the reaction of group C was the most serious. The content of collagenous fiber, hyaluronic acid and fibronectin in vocal fold lamina layer was significantly higher than that in normal group (P<0.05). Different degrees of fiber proliferation were observed in all groups. The content of each component of vocal fold lamina layer tended to be normal slightly higher level in 28 d. Observation by electron microscope showed that there were no significant differences in A, B, C, D, E in 28 d after intervention.
  
  
  CONCLUSIONS
  Recoverable damage repair process can be detected in rabbit vocal after intervened with PDT, which began in 7 d and basically completed in 28 d. In a certain concentration (10%-20%) and dose range (100-200 mW). The higher of photodynamic dose, the more serious of the damage. And the damage was basically reversible.
authors.affiliation: Department of Otorhinolaryngology, Second Hospital of Tianjin Medical University, Tianjin 300211, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Liu
authors.affiliation: Email: ywhuanghss@163.com.
authors.forename: Yongwang
authors.initials: Y
authors.lastname: Huang
authors.forename: Shanshan
authors.initials: S
authors.lastname: Wang
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Li
authors.forename: Huijuan
authors.initials: H
authors.lastname: Yin
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Gao
mesh_terms: D000818:Animals; D007818:Laryngeal Diseases / Q000188:drug therapy*; D008027:Light; D010778:Photochemotherapy; D011817:Rabbits; D014827:Vocal Cords / Q000187:drug effects* / Q000293:injuries* / Q000473:pathology; D014945:Wound Healing