title: Effects of gamma irradiation on collagen damage and remodeling.
abstract: OBJECTIVE
  To evaluate the dose-time dependences of structural changes occurring in collagen within 24 hours to three months after gamma-irradiation at doses from 2-40 Gy in vivo.
  
  
  METHODS
  Rat's tail tendon was chosen as in vivo model, with its highly ordered collagen structure allowing the changes to be interpreted unambiguously. Macromolecular level (I) was investigated by differential scanning calorimetry (DSC); fibers and bundles level (II) by laser scanning microscopy (LSM), and bulk tissue microstructural level (III) by cross-polarization optical coherence tomography (CP-OCT).
  
  
  RESULTS
  For (I), the formation of molecular cross-links and breaks appeared to be a principal mechanism of collagen remodeling, with the cross-links number dependent on radiation dose. Changes on level (II) involved primary, secondary and tertiary bundles splitting in a day and a week after irradiation. Bulk collagen microstructure (III) demonstrated early widening of the interference fringes on CP-OCT images observed to occur in the tendon as result of this splitting. At all three levels, the observed collagen changes demonstrated complete remodeling within ∼ a month following irradiation.
  
  
  CONCLUSIONS
  The time course and dose dependencies of the observed collagen changes at different levels of its hierarchy further contribute to elucidating the role of connective tissue in the radiotherapy process.
authors.affiliation: Nizhny Novgorod State Medical Academy , Nizhny Novgorod , Russian Federation.
authors.forename: Anna
authors.initials: A
authors.lastname: Maslennikova
authors.forename: Marina
authors.initials: M
authors.lastname: Kochueva
authors.forename: Natalia
authors.initials: N
authors.lastname: Ignatieva
authors.forename: Alex
authors.initials: A
authors.lastname: Vitkin
authors.forename: Olga
authors.initials: O
authors.lastname: Zakharkina
authors.forename: Vladislav
authors.initials: V
authors.lastname: Kamensky
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Sergeeva
authors.forename: Elena
authors.initials: E
authors.lastname: Kiseleva
authors.forename: Victor
authors.initials: V
authors.lastname: Bagratashvili
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D003094:Collagen / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D003238:Connective Tissue / Q000737:chemistry / Q000293:injuries / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000009:adverse effects*; D008297:Male; D018613:Microscopy, Confocal; D046912:Multiprotein Complexes / Q000737:chemistry / Q000528:radiation effects; D011833:Radiation Injuries, Experimental / Q000378:metabolism / Q000473:pathology; D051381:Rats; D013710:Tendons / Q000737:chemistry / Q000473:pathology / Q000528:radiation effects; D041623:Tomography, Optical Coherence
chemical_list: D046912:Multiprotein Complexes; D003094:Collagen
keywords: Collagen; differential scanning calorimetry; gamma irradiation; laser scanning microscopy; optical coherence tomography; radiation damage