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 results suggest that use of high - dose TXA in older patients in conjunction with cardiopulmonary bypass and open - chamber cardiac surgery is associated with clinical seizures in susceptible patients .
### Output Text:
CONCLUSION : Our results suggest that use of high - dose <span class="chemical">TXA</span> in older patients in conjunction with cardiopulmonary bypass and open - chamber cardiac surgery is associated with clinical seizures in susceptible patients . 