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: These results support the conclusion that NO plays a role of endogenous convulsant in rat model of lindane seizures .
### Output Text:
These results support the conclusion that <span class="chemical">NO</span> plays a role of endogenous convulsant in rat model of <span class="chemical">lindane</span> seizures . 