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: However , in the ADR - nephropathy group , numerous apoptotic cells were identified in the tubulointerstitial areas .
### Output Text:
However , in the <span class="chemical">ADR</span> - nephropathy group , numerous apoptotic cells were identified in the tubulointerstitial areas . 