title: Upregulation of inducible nitric oxide synthase and nitrotyrosine expression in primary knee osteoarthritis.
abstract: BACKGROUND
  To investigate nitrite and inducible nitric oxide synthase (iNOS) levels in the plasma and synovial fluid of patients with primary knee osteoarthritis (OA) and to determine protein nitrotyrosine in synovial tissue of OA patients.
  
  
  METHODS
  Thirty patients and 30 healthy controls were recruited into the present study. Plasma and synovial fluid nitrite levels were measured using Griess reaction. Plasma and synovial fluid iNOS concentrations were analyzed by enzyme-linked immunosorbent assay. Nitrotyrosine was detected immunohistochemically in synovial tissue of OA patients.
  
  
  RESULTS
  Plasma and synovial fluid nitrite concentration in the OA group were significantly higher than those in the healthy control group were (p = 0.007 and p = 0.012). Furthermore, plasma iNOS levels were significantly higher in the OA group than those in healthy control group were (p = 0.04). Moreover, nitrotyrosine was detected immunohistochemically in macrophages, synovial lining layer and synoviocytes of synovial tissue in the OA group.
  
  
  CONCLUSIONS
  These findings indicate that reactive nitrogen species and nitrotyrosine-containing proteins may be involved in the joint destruction process, and play a potential role in the pathogenesis of knee osteoarthritis.
authors.forename: Tanyawan
authors.initials: T
authors.lastname: Suantawee
authors.forename: Saran
authors.initials: S
authors.lastname: Tantavisut
authors.forename: Sirichai
authors.initials: S
authors.lastname: Adisakwattana
authors.forename: Thanathep
authors.initials: T
authors.lastname: Tanpowpong
authors.forename: Aree
authors.initials: A
authors.lastname: Tanavalee
authors.forename: Pongsak
authors.initials: P
authors.lastname: Yuktanandana
authors.forename: Wilai
authors.initials: W
authors.lastname: Anomasiri
authors.forename: Benjamad
authors.initials: B
authors.lastname: Deepaisarnsakul
authors.forename: Sittisak
authors.initials: S
authors.lastname: Honsawek
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D052247:Nitric Oxide Synthase Type II / Q000097:blood / Q000378:metabolism*; D020370:Osteoarthritis, Knee / Q000097:blood / Q000201:enzymology / Q000378:metabolism*; D013582:Synovial Fluid / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C002744:3-nitrotyrosine; D014443:Tyrosine; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II