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: Thirteen biopsies were performed from stable functioning renal allografts with informed consent ( nonepisode biopsy ) and the other 13 were from dysfunctional renal allografts with a clinical indication for biopsy ( episode biopsy ) .
### Output Text:
Thirteen biopsies were performed from stable functioning renal allografts with informed consent ( nonepisode biopsy ) and the other 13 were from dysfunctional renal allografts with a clinical indication for biopsy ( episode biopsy ) . 