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 : Our data suggest that Asian patients may be at increased risk of hyponatremia and / or SIADH associated with vincristine use .
### Output Text:
CONCLUSION : Our data suggest that Asian patients may be at increased risk of hyponatremia and / or SIADH associated with <span class="chemical">vincristine</span> use . 