title: Structural changes of smooth muscle in congenital ureteropelvic junction obstruction.
abstract: OBJECTIVE
  Ureteropelvic junction (UPJ) obstruction is the most common cause of congenital hydronephrosis. Previous studies have reported that the excess amount of collagen restricting mobility and resiliency of the UPJ is the result of an impaired collagen production by anomalous smooth muscle cells (SMCs). Our purpose was to evaluate the role of SMC differentiation in the pathogenesis of UPJ obstruction.
  
  
  METHODS
  Surgical specimens of UPJ from 21 patients (8 girls/13 boys) who were subjected to dismembered pyeloplasty were examined immunohistochemically using monoclonal antibodies against smooth muscle (SM) myosin heavy chain isoforms including SM1, SM2, and SMemb. The age ranged from 1 month to 13 years. Ureteropelvic walls taken from 14 forensic autopsy cases, with no urological abnormalities, served as age-matched control group.
  
  
  RESULTS
  The immunohistochemical expression of SM1 and SM2 in UPJ obstruction was significantly increased when compared with controls (P < .05). In contrast, there was no statistical difference of expression of SMemb.
  
  
  CONCLUSIONS
  Our findings supported the hypothesis that the primary anomaly in UPJ obstruction may be attributed to a malfunction of SMCs in the ureter.
authors.affiliation: Department of Pediatric Surgery, Dr Behcet Uz Children's Hospital, Izmir, 35210, Turkey. munevver.hosgor@superonline.com
authors.forename: Munevver
authors.initials: M
authors.lastname: Hosgor
authors.forename: Irfan
authors.initials: I
authors.lastname: Karaca
authors.forename: Cagnur
authors.initials: C
authors.lastname: Ulukus
authors.forename: Erdener
authors.initials: E
authors.lastname: Ozer
authors.forename: Erdem
authors.initials: E
authors.lastname: Ozkara
authors.forename: Bulent
authors.initials: B
authors.lastname: Sam
authors.forename: Basak
authors.initials: B
authors.lastname: Ucan
authors.forename: Senay
authors.initials: S
authors.lastname: Kurtulus
authors.forename: Aytac
authors.initials: A
authors.lastname: Karkiner
authors.forename: Gunyuz
authors.initials: G
authors.lastname: Temir
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007682:Kidney Pelvis; D008297:Male; D009130:Muscle, Smooth / Q000473:pathology*; D014517:Ureteral Obstruction / Q000209:etiology*