title: Ultrastructural changes in articular cartilages of immature beagle dogs dosed with difloxacin, a fluoroquinolone.
abstract: The ultrastructural features of quinolone-induced arthropathy were studied in the humeral and femoral heads of nine skeletally immature Beagle dogs (3 months old) that were dosed orally with difloxacin at 300 mg/kg body weight and euthanatized 24, 36, or 48 hours later in groups of three. Three age-matched dogs were given a placebo and euthanatized after 48 hours. Mitochondria in chondrocytes had significantly greater cross-sectional areas (P less than 0.05) in electron micrographs from dogs euthanatized after 48 hours of treatment than did those in other groups. There was also a significantly greater percentage of chondrocytes with swollen mitochondria in treated dogs than in the controls (P less than 0.05). These changes preceded the necrosis observed in some chondrocytes in the dogs of the 48-hour group. Disruption of extracellular matrix was first observed in the pericellular matrix of necrotic chondrocytes, indicating that this change was secondary to the changes in chondrocytes. Fissures within cartilages apparently resulted from the loss of the normal association of proteoglycans with collagen fibrils.
authors.affiliation: Department of Pathobiology, Purdue University School of Veterinary Medicine, West Lafayette, IN.
authors.forename: J E
authors.initials: JE
authors.lastname: Burkhardt
authors.forename: M A
authors.initials: MA
authors.lastname: Hill
authors.forename: J J
authors.initials: JJ
authors.lastname: Turek
authors.forename: W W
authors.initials: WW
authors.lastname: Carlton
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000633:toxicity*; D002358:Cartilage, Articular / Q000187:drug effects* / Q000648:ultrastructure; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000633:toxicity; D004285:Dogs / Q000033:anatomy & histology*; D005270:Femur Head / Q000187:drug effects* / Q000648:ultrastructure; D024841:Fluoroquinolones; D006811:Humerus / Q000187:drug effects* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; C047225:difloxacin