title: Determination of urinary myo-inositol concentration by an improved enzymatic cycling method using myo-inositol dehydrogenase from Flavobacterium sp.
abstract: BACKGROUND
  To determine myo-inositol more accurately, we improved the enzymatic cycling method.
  
  
  METHODS
  We screened myo-inositol dehydrogenase (MIDH; EC.1.1.1.18) from Flavobacterium sp., which was highly specific to myo-inositol. We measured urinary myo-inositol/creatinine ratio 2 h after 75-g oral glucose tolerance test (2 h MI) of 71 volunteers, and investigated the relationship between diabetes and urinary myo-inositol concentration.
  
  
  RESULTS
  The calibration curve was linear (r = 1.00) up to 2000 micromol/l, and the detection limit was 10 micromol/l. Within-run and between-run CVs were 0.5-1.1% and 0.4-1.3%, respectively. The 2 h MI of impaired fasting glycemia (IFG; 65.1 +/- 46.6 mg/g Cr, P < 0.005), impaired glucose tolerance (IGT; 85.0 +/- 73.7 mg/g Cr, P < 0.001) and diabetes (163.4 +/- 73.7 mg/g Cr, P < 0.0001) increased significantly compared with that of normal glucose tolerance (NGT; 24.0 +/- 14.4 mg/g Cr). From receiver operating characteristic analyses on 2 h MI, with 50 mg/g Cr as a tentative cutoff value to detect diabetes, the sensitivity and specificity were 100% and 77%, respectively. With 40 mg/g Cr as a tentative cutoff value to detect NGT, the sensitivity and specificity were 74% and 85%, respectively.
  
  
  CONCLUSIONS
  The myo-inositol measurement method demonstrated high specificity and yielded accurate results. The results of clinical trials suggested that 2 h MI could not only determine diabetes but also distinguish IFG and IGT from NGT.
authors.affiliation: Diagnostics R&D Department, Fine Chemicals and Diagnostics Division, Health Care Company, Asahi Kasei Corporation, 632-1, Mifuku, Ohito-cho, Tagata-gun, Shizuoka 410-2321, Japan. yamakoshi.mb@om.asahi-kasei.co.jp
authors.forename: Masaru
authors.initials: M
authors.lastname: Yamakoshi
authors.forename: Mamoru
authors.initials: M
authors.lastname: Takahashi
authors.forename: Takuji
authors.initials: T
authors.lastname: Kouzuma
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Imamura
authors.forename: Isami
authors.initials: I
authors.lastname: Tsuboi
authors.forename: Shoji
authors.initials: S
authors.lastname: Kawazu
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamagata
authors.forename: Makoto
authors.initials: M
authors.lastname: Tominaga
authors.forename: Masayuki
authors.initials: M
authors.lastname: Noritake
mesh_terms: D000328:Adult; D005260:Female; D005417:Flavobacterium / Q000201:enzymology*; D006801:Humans; D007294:Inositol / Q000652:urine*; D008297:Male; D008875:Middle Aged; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D007294:Inositol; D010744:Phosphoric Monoester Hydrolases; C053087:inositol-1,4-bisphosphate 1-phosphatase