title: Stability of 3-bromotyrosine in serum and serum 3-bromotyrosine concentrations in dogs with gastrointestinal diseases.
abstract: BACKGROUND
  3-Bromotyrosine (3-BrY) is a stable product of eosinophil peroxidase and may serve as a marker of eosinophil activation. A gas chromatography/mass spectrometry method to measure 3-BrY concentrations in serum from dogs has recently been established and analytically validated. The aims of this study were to determine the stability of 3-BrY in serum, to determine the association between peripheral eosinophil counts and the presence of an eosinophilic infiltrate in the gastrointestinal tract, and to compare serum 3-BrY concentrations in healthy dogs (n = 52) and dogs with eosinophilic gastroenteritis (EGE; n = 27), lymphocytic-plasmacytic enteritis (LPE; n = 25), exocrine pancreatic insufficiency (EPI; n = 26), or pancreatitis (n = 27).
  
  
  RESULTS
  Serum 3-BrY concentrations were stable for up to 8, 30, and 180 days at 4°C, -20°C, and -80°C, respectively. There was no significant association between peripheral eosinophil count and the presence of eosinophils in the GI tissues (P = 0.1733). Serum 3-BrY concentrations were significantly higher in dogs with EGE (median [range] = 5.04 [≤0.63-26.26] μmol/L), LPE (median [range] = 3.60 [≤0.63-15.67] μmol/L), and pancreatitis (median [range] = 1.49 [≤0.63-4.46] μmol/L) than in healthy control dogs (median [range] = ≤0.63 [≤0.63-1.79] μmol/L; P < 0.0001), whereas concentrations in dogs with EPI (median [range] = 0.73 [≤0.63-4.59] μmol/L) were not different compared to healthy control dogs.
  
  
  CONCLUSIONS
  The present study revealed that 3-BrY concentrations were stable in serum when refrigerated and frozen. No relationship between peripheral eosinophil count and the presence of eosinophils infiltration in the GI tissues was found in this study. In addition, serum 3-BrY concentrations were increased in dogs with EGE, but also in dogs with LPE and pancreatitis. Further studies are needed to determine whether measurement of 3-BrY concentrations in serum may be useful to assess patients with suspected or confirmed EGE or LPE.
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. psatta@cvm.tamu.edu.|Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, 10900, Thailand. psatta@cvm.tamu.edu.
authors.forename: Panpicha
authors.initials: P
authors.lastname: Sattasathuchana
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. ngruetzner@cvm.tamu.edu.|Department for Clinical Veterinary Medicine, Clinic for Swine, University of Bern, Bern, 3012, Switzerland. ngruetzner@cvm.tamu.edu.
authors.forename: Niels
authors.initials: N
authors.lastname: Grützner
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. rlopes@cvm.tamu.edu.
authors.forename: Rosana
authors.initials: R
authors.lastname: Lopes
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. bguard@cvm.tamu.edu.
authors.forename: Blake C
authors.initials: BC
authors.lastname: Guard
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. jsuchodolski@cvm.tamu.edu.
authors.forename: Jan S
authors.initials: JS
authors.lastname: Suchodolski
authors.affiliation: Gastrointestinal Laboratory, College of Veterinary Medicine, Texas A&M University, College Station, Texas, 77843, USA. jsteiner@cvm.tamu.edu.
authors.forename: Jörg M
authors.initials: JM
authors.lastname: Steiner
mesh_terms: D000818:Animals; D015415:Biomarkers; D016022:Case-Control Studies; D004283:Dog Diseases / Q000097:blood*; D004285:Dogs; D004804:Eosinophils / Q000378:metabolism*; D005260:Female; D005767:Gastrointestinal Diseases / Q000097:blood / Q000378:metabolism / Q000662:veterinary*; D008297:Male; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014443:Tyrosine; C118327:3-bromotyrosine