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: This was further supported by results showing that nonconvulsive doses of NMDA and pilocarpine were synergistic , resulting in status epilepticus and subsequent mortality .
### Output Text:
This was further supported by results showing that nonconvulsive doses of <span class="chemical">NMDA</span> and <span class="chemical">pilocarpine</span> were synergistic , resulting in status epilepticus and subsequent mortality . 