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: We compared these results with those previously obtained with kainic acid ( KA ) , a potent glutamate agonist .
### Output Text:
We compared these results with those previously obtained with <span class="chemical">kainic acid</span> ( <span class="chemical">KA</span> ) , a potent <span class="chemical">glutamate</span> agonist . 