In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: RESULTS : Histopathological examination of the kidneys of rats treated with ADR revealed focal areas of mesangial proliferation and mild tubulointerstitial inflammation .
### Output Text:
RESULTS : Histopathological examination of the kidneys of rats treated with <span class="chemical">ADR</span> revealed focal areas of mesangial proliferation and mild tubulointerstitial inflammation . 