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 conclude that neuroactive steroids are highly effective in protecting against pilocarpine - and kainic acid - induced seizures and status epilepticus in mice , and may be of utility in the treatment of some forms of status epilepticus in humans .
### Output Text:
We conclude that neuroactive <span class="chemical">steroids</span> are highly effective in protecting against <span class="chemical">pilocarpine</span> - and <span class="chemical">kainic acid</span> - induced seizures and status epilepticus in mice , and may be of utility in the treatment of some forms of status epilepticus in humans . 