title: Sudan black B reduces autofluorescence in murine renal tissue.
abstract: BACKGROUND
  Renal tissue emits intense autofluorescence, making it difficult to differentiate specific immunofluorescence signals and thus limiting its application to clinical biopsy material.
  
  
  OBJECTIVE
  To identify and minimize autofluorescence of renal tissue and demonstrate a simple, efficient method to reduce autofluorescence using Sudan black B.
  
  
  METHODS
  In this study, the sources and features of autofluorescence emitted from kidney tissue were examined. Broad autofluorescence was visualized in both frozen and paraffin kidney sections of normal mice and mice with Adriamycin-induced nephropathy using confocal laser scanning microscopy. Autofluorescence appeared in commonly used 4',6-diamidino-2-phenylindole, fluorescein isothiocyanate, and Texas Red channels but not in far-red channel, and emitted extensively from red cells, injured tubulointersitial cells, and protein casts in diseased kidney. To eliminate autofluorescence, Sudan black B was used on formaldehyde-fixed paraffin sections and frozen sections of mouse kidney. The effects of Sudan black B in various concentrations were tested on kidney tissue.
  
  
  RESULTS
  The 0.1% Sudan black B effectively blocked autofluorescence from both paraffin and frozen sections without adversely affecting specific fluorescence signals. Interestingly, the solvent for Sudan black B, 70% ethanol, was also shown to reduce autofluorescence on frozen sections, but not on paraffin sections.
  
  
  CONCLUSIONS
  This study demonstrates a simple, efficient, and cost-effective method to reduce autofluorescence using Sudan black B, and also provides a comprehensive approach to identify and minimize autofluorescence of renal tissue.
authors.affiliation: Department of Pediatrics, Provincial Hospital Affiliated to Shandong University, Jinan, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.forename: Dong
authors.initials: D
authors.lastname: Zheng
authors.forename: Qi
authors.initials: Q
authors.lastname: Cao
authors.forename: Ya
authors.initials: Y
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Harris
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D001391:Azo Compounds; D004396:Coloring Agents; D004317:Doxorubicin / Q000633:toxicity; D005453:Fluorescence; D005629:Frozen Sections; D007668:Kidney / Q000033:anatomy & histology* / Q000473:pathology; D007674:Kidney Diseases / Q000139:chemically induced / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009281:Naphthalenes; D016612:Paraffin Embedding; D013194:Staining and Labeling / Q000379:methods
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D009281:Naphthalenes; D004317:Doxorubicin; C016118:Sudan Black B