title: An improved system for quantifying AgNOR and PCNA in canine tumors.
abstract: BACKGROUND
  Quantifying silver stained nucleolar organizer regions (AgNORs) and proliferation cell nuclear antigens (PCNA) are useful techniques to measure proliferative activity of tumor cells; however, the nonspecific deposition of stains and overlappings of AgNOR and PCNA counts between grades of tumors hamper their applications.
  
  
  METHODS
  Fifty-two surgical specimens from dogs, including mast cell tumors, perianal gland tumors and hyperplasias, fibromas, fibrosarcomas, and normal tissues were studied. The 3 microns dewaxed sections of formalin-fixed tissues were stained to detect AgNORs by a modified inverted incubation technique in a newly developed silver staining device. Data were collected and analyzed using a high-resolution digital microscope camera and image analysis software. Sequential sections were also stained for PCNA using an immunohistochemical method.
  
  
  RESULTS
  The improved system for quantifying AgNOR provided more accurate and non-overlapping mean AgNOR counts, which enable us to distinguish benign states from malignant changes. The mean AgNOR cut-off points that discriminated grade II or III mast cell tumors from grade I, perianal gland carcinomas from adenomas (or hyperplasia), fibrosarcomas from non-fibrosarcoma tissues, were 6.0, 14.1, 9.4, and 8.8 respectively. The mean AgNOR areas, relative AgNOR areas, and PCNA positive rates of some malignant and non-malignant tissues (benign tumor and normal tissues) were significantly different (P < 0.05).
  
  
  CONCLUSIONS
  This improved system is a sensitive and rather precise method for quantifying the AgNOR and PCNA. It provides a valuable objective measurement for differentiating benign and malignant tumors.
authors.affiliation: Department of Veterinary Medicine, National Taiwan University, Taipei, R.O.C.
authors.forename: L C
authors.initials: LC
authors.lastname: Hung
authors.forename: V F
authors.initials: VF
authors.lastname: Pong
authors.forename: C R
authors.initials: CR
authors.lastname: Cheng
authors.forename: F I
authors.initials: FI
authors.lastname: Wong
authors.forename: R M
authors.initials: RM
authors.lastname: Chu
mesh_terms: D000694:Anal Gland Neoplasms / Q000145:classification* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D004285:Dogs; D005350:Fibroma / Q000145:classification / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D005354:Fibrosarcoma / Q000145:classification / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D016014:Linear Models; D012515:Mast-Cell Sarcoma / Q000145:classification / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D009697:Nucleolus Organizer Region; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis*; D016622:Silver Staining / Q000379:methods
chemical_list: D018809:Proliferating Cell Nuclear Antigen