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: CONCLUSION : Cisapride affects jejunal contraction characteristics and some symptoms in IBS .
### Output Text:
CONCLUSION : <span class="chemical">Cisapride</span> affects jejunal contraction characteristics and some symptoms in IBS . 