title: Observation of sGAG content of human hip joint cartilage in different old age groups based on EPIC micro-CT.
abstract: OBJECTIVE
  To observe the age-related changes of sulfated glycosaminoglycan (sGAG) content of hip joint cartilage of elderly people based on Equilibrium Partitioning of an Ionic Contrast Agent (EPIC) micro-CT.
  
  
  METHODS
  Seventy human hip cartilage-bone samples were collected from hip-fracture patients (ages 51-96) and divided into five groups (10 years in an age group). They were first immersed in 20% concentration of the contrast agent Meglumine Diatrizoate (MD) for 6 h at 37 °C, and then scanned by micro-CT. Following scanning, samples were stained for sGAG with toluidine blue. The X-ray attenuation and sGAG optical density were calculated by image processing. The correlation between X-ray attenuation and sGAG optical density was then analyzed.
  
  
  RESULTS
  The X-ray mean attenuation of the cartilage increased by 18.81% from the 50-80 age groups (p < 0.01), but decreased by 7.15% in the 90 age group compared to the 80 age group. The X-ray mean attenuation of the superficial layer and middle layer increased by 31.60 % and 44.68% from the 50-80 age groups, respectively (p < 0.01), but reduced by 4.67% and 6.05% separately in the 90 age group. However, the deep layer showed no significant change with aging. The sGAG optical density showed a linear correlation (r = -0.91, p < 0.01) with the X-ray attenuation.
  
  
  CONCLUSIONS
  The sGAG content of hip joint cartilage varied with aging in elderly people. The changes in superficial layer and middle layer were more evident than deep layer.
authors.affiliation: Key Laboratory of the Ministry of Education for Biomechanics and Mechanobiology, School of Biological Science & Medical Engineering, Beihang University , Beijing , China and.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Li
authors.forename: Xi-Ran
authors.initials: XR
authors.lastname: Cai
authors.forename: Fan
authors.initials: F
authors.lastname: Fan
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Niu
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Li
authors.forename: De-Yu
authors.initials: DY
authors.lastname: Li
authors.forename: Yu-Bo
authors.initials: YB
authors.lastname: Fan
authors.forename: Yi-Xian
authors.initials: YX
authors.lastname: Qin
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000473:pathology*; D003287:Contrast Media; D006025:Glycosaminoglycans / Q000378:metabolism*; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000473:pathology*; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; C013786:A73025
keywords: EPIC micro-CT; Elderly people; hip joint cartilage; layered structure; sGAG