title: Interplay of vitamin D and nitric oxide in post-menopausal knee osteoarthritis.
abstract: OBJECTIVE
  Mounting evidence has presented nitric oxide (NO) and vitamin D (vitD) as having independently complex roles in osteoarthritis (OA). However, a mechanistic or an observational connection between them has never been investigated in the disease. This study investigates the correlation between circulating 25-hydroxyvitamin D [25(OH)D] and total NO as nitrate/nitrite (NO x ) in patients with knee OA.
  
  
  METHODS
  The recruited subjects comprised 36 post-menopausal women with knee OA, ages 50-60 years, as well as 10 healthy males, 20-30 years of age. 25(OH)D and NO x levels were determined using high-performance liquid chromatography and spectrophotometrically using Griess reaction, respectively.
  
  
  RESULTS
  The mean (SEM) 25(OH)D and NO x concentrations of OA patients were 25.0 (1.6) ng/mL and 32.45 (2.18) μM, respectively, and 35.4 (2.1) ng/mL and 25.49 (2.23) μM, respectively, for controls. Comparison of mean 25(OH)D and NO x concentrations of OA patients and controls yielded significant results (P = 0.001 and 0.034, respectively). NO notably decreased with decreasing 25(OH)D concentration in patients. However, significant results in terms of mean NO x concentration were observed in the comparison of normal and deficient vitD OA groups (P = 0.048).
  
  
  CONCLUSIONS
  Results suggest that vitD increases NO production and inducible NO synthase expression in osteoarthritic chondrocytes possibly leading to a protective effect.
authors.affiliation: Biochemistry Department, Faculty of Pharmacy and Biotechnology, German University in Cairo, Al Tagamoa Al Khames, New Cairo, 11835, Egypt.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Abu El Maaty
authors.forename: Rasha S
authors.initials: RS
authors.lastname: Hanafi
authors.forename: Samir
authors.initials: S
authors.lastname: El-Badawy
authors.forename: Mohamed Z
authors.initials: MZ
authors.lastname: Gad
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D020370:Osteoarthritis, Knee / Q000378:metabolism*; D017698:Postmenopause / Q000378:metabolism*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D009566:Nitrates; D009573:Nitrites; D014807:Vitamin D; D009569:Nitric Oxide; C104450:25-hydroxyvitamin D