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 : The replacement of the last dose or the last two doses of mesna with dexamethasone reduced the increase in bladder wet weight induced by IFS by 84 . 79 % and 89 . 13 % , respectively .
### Output Text:
RESULTS : The replacement of the last dose or the last two doses of <span class="chemical">mesna</span> with <span class="chemical">dexamethasone</span> reduced the increase in bladder wet weight induced by <span class="chemical">IFS</span> by 84 . 79 % and 89 . 13 % , respectively . 