title: Use of colorimetric test strips for monitoring the effect of hemodialysis on salivary nitrite and uric acid in patients with end-stage renal disease: a proof of principle.
abstract: BACKGROUND
  Initial screening of potential biomarkers for monitoring dialysis was performed with saliva samples collected from patients with end-stage renal disease (ESRD). A more thorough analysis of the most promising markers identified in the initial screening was conducted with saliva samples acquired at hourly intervals throughout dialysis to monitor analyte concentrations as dialysis progressed. We observed that salivary nitrite (NO(2)(-)) and uric acid (UA) concentrations consistently decreased as dialysis proceeded.
  
  
  METHODS
  Solution-based colorimetric-detection chemistries for NO(2)(-) and UA were converted to a test strip format to produce a simple method for semiquantitatively measuring NO(2)(-) and UA concentrations in the clinic or at the patient's home. We assessed the test strips with saliva samples collected from both ESRD patients undergoing dialysis and healthy control volunteers to qualitatively monitor the effect of dialysis on salivary NO(2)(-) and UA. We used computer software to analyze digital images of the resulting test strip color intensities.
  
  
  RESULTS
  Test strip measurements showed that mean salivary concentrations of NO(2)(-) and UA were decreased in ESRD patients by 86% and 39%, respectively, compared with 15% and 9% for time-matched controls. Comparison of test strip results with calibrated solution-based assays suggests that the test strips can semiquantitatively measure salivary concentrations of NO(2)(-) and UA.
  
  
  CONCLUSIONS
  The colorimetric test strips monitored changes in salivary NO(2)(-) and UA concentrations that occurred in ESRD patients during dialysis. The test strips may prove useful for noninvasively evaluating dialysis progress and may also be useful for monitoring renal disease status.
authors.affiliation: Department of Chemistry, Tufts University, Medford, MA 02155, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Blicharz
authors.forename: David M
authors.initials: DM
authors.lastname: Rissin
authors.forename: Michaela
authors.initials: M
authors.lastname: Bowden
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Hayman
authors.forename: Christopher
authors.initials: C
authors.lastname: DiCesare
authors.forename: Jasvinder S
authors.initials: JS
authors.lastname: Bhatia
authors.forename: Nerline
authors.initials: N
authors.lastname: Grand-Pierre
authors.forename: Walter L
authors.initials: WL
authors.lastname: Siqueira
authors.forename: Eva J
authors.initials: EJ
authors.lastname: Helmerhorst
authors.forename: Joseph
authors.initials: J
authors.lastname: Loscalzo
authors.forename: Frank G
authors.initials: FG
authors.lastname: Oppenheim
authors.forename: David R
authors.initials: DR
authors.lastname: Walt
mesh_terms: D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D006262:Health; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism*; D009573:Nitrites / Q000032:analysis* / Q000378:metabolism; D010084:Oxidation-Reduction; D011934:Reagent Strips; D006435:Renal Dialysis; D012463:Saliva / Q000737:chemistry*; D014527:Uric Acid / Q000032:analysis* / Q000378:metabolism
chemical_list: D009573:Nitrites; D011934:Reagent Strips; D014527:Uric Acid