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: Bladder afferent cells in the L6 - S1 DRG labeled by Fluorogold ( 40 microliters ) injected into the bladder wall did not exhibit NOS - IR in control animals ; however , following chronic CYP administration , a significant percentage of bladder afferent neurons were NOS - IR : L6 ( 19 . 8 + / - 4 . 6 % ) and S1 ( 25 . 3 + / - 2 . 9 % ) .
### Output Text:
Bladder afferent cells in the L6 - S1 DRG labeled by Fluorogold ( 40 microliters ) injected into the bladder wall did not exhibit NOS - IR in control animals ; however , following chronic <span class="chemical">CYP</span> administration , a significant percentage of bladder afferent neurons were NOS - IR : L6 ( 19 . 8 + / - 4 . 6 % ) and S1 ( 25 . 3 + / - 2 . 9 % ) . 