title: Apolipoprotein AII levels are associated with the UP/UCr levels in idiopathic steroid-sensitive nephrotic syndrome.
abstract: BACKGROUND
  Various humoral factors have been proposed as causal agents of idiopathic steroid-sensitive nephrotic syndrome (ISSNS), resulting in varying data. We used mass spectrometry (MS) to analyze serum proteins in a search for proteins that might be involved in ISSNS pathophysiology.
  
  
  METHODS
  Serial serum samples were obtained from 33 children with ISSNS. Samples were collected during Phase A1 [the acute phase prior to steroid treatment (STx)], Phase A2 (remission with STx), and Phase A3 (remission without any medication). We also included age- and sex-matched two control groups comprising children with normal urinalysis (Group B) and children with a nephrotic syndrome other than ISSNS (Group C). The urinary protein/urinary creatinine (UP/UCr) ratios were not statistically different between Phase A1 and Group C. Samples were analyzed using surface-enhanced laser desorption/ionization time of flight MS.
  
  
  RESULTS
  A total of 207 peptide ion peaks were detected in the range of m/z 2000-10000. Four peptide ions (m/z 6444, 6626, 8695, and 8915) were detected at significant elevation during Phase A1 compared with Phase A2, Phase A3, and Group C. The intensities of m/z 6444 and 8695 were higher in Phase A3 than in Group B. There were significant correlations between the intensities of m/z 6626, 8695, and 8915 and UP/UCr levels. The m/z 8695 was identified as apolipoprotein AII.
  
  
  CONCLUSIONS
  Apolipoprotein AII was detected as a protein associated with the UP/UCr levels in pediatric ISSNS. Our findings present an interesting starting point for further investigation into the pathophysiology of ISSNS.
authors.affiliation: Department of Pediatrics, Jichi Medical University, 3311-1 Yakushiji Shimotsuke, Tochigi, 329-0498, Japan, tkanai@jichi.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kanai
authors.forename: Takanori
authors.initials: T
authors.lastname: Yamagata
authors.forename: Takane
authors.initials: T
authors.lastname: Ito
authors.forename: Jun
authors.initials: J
authors.lastname: Odaka
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
authors.forename: Jun
authors.initials: J
authors.lastname: Aoyagi
authors.forename: Mariko Y
authors.initials: MY
authors.lastname: Momoi
mesh_terms: D000293:Adolescent; D016633:Apolipoprotein A-II / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy / Q000378:metabolism*; D011507:Proteinuria / Q000378:metabolism*; D013256:Steroids / Q000627:therapeutic use*
chemical_list: D016633:Apolipoprotein A-II; D013256:Steroids; D003404:Creatinine