title: Computerized photocolorimetric analysis of the effects of intraarticular betamethasone on the proteoglycan concentration of leporine knee cartilage matrix: influence of the number of intraarticular injections.
abstract: OBJECTIVE
  To study the effects of repeated injections of betamethasone on proteoglycan concentration in the articular cartilage of normal knees of Californian rabbits of both sexes.
  
  
  METHODS
  Eighty animals were randomly divided into eight groups of ten animals each. Three control groups (saline solution injected or not) and five study groups - therapeutical doses, repeated or not, of betamethasone injected into the right knee of each animal at weekly intervals. After eight days from the last injection, sections of articular cartilage from tibial plateaus collected from weight-bearing surfaces were stained with hematoxylin and eosin for light microscopy analysis and with safranin O for the proteoglycan content assay. The staining intensity of safranin O was quantified by histomorphometry using an Olympus BX 50 microscope and a microcomputer with the Image Pro-plus 4.5O software.
  
  
  RESULTS
  Animals receiving one, two and four betamethasone injections showed no differences when compared to normal controls. Animals receiving six and eight injections had a significant decrease in safranin O staining intensity (p < 0.05) as compared to the control groups and the other study groups.
  
  
  CONCLUSIONS
  A decrease in the concentration of articular cartilage proteoglycans dependent on repeated betamethasone injection was effectively demonstrated.
authors.affiliation: Graduate Program in Clinics and Surgery, Universidade Federal do Paraná - UFPR, Curitiba, PR, Brazil. albano_mauro@yahoo.com.br
authors.forename: Mauro Batista
authors.initials: MB
authors.lastname: Albano
authors.forename: Gabriel Paulo
authors.initials: GP
authors.lastname: Skroch
authors.forename: Sérgio Ossamu
authors.initials: SO
authors.lastname: Ioshii
authors.forename: Xavier Soler
authors.initials: XS
authors.lastname: Grahels
authors.forename: Paulo Gilberto Cimbalista
authors.initials: PG
authors.lastname: de Alencar
authors.forename: Jorge Eduardo Fouto
authors.initials: JE
authors.lastname: Matias
mesh_terms: D000818:Animals; D001623:Betamethasone / Q000008:administration & dosage* / Q000494:pharmacology; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism*; D003124:Colorimetry; D003201:Computers; D005260:Female; D007270:Injections, Intra-Articular / Q000706:statistics & numerical data; D007719:Knee Joint / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D011509:Proteoglycans / Q000187:drug effects* / Q000378:metabolism*; D011817:Rabbits
chemical_list: D011509:Proteoglycans; D001623:Betamethasone