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: Both cell elements may suffer in common from metabolic disturbance and neurotransmitter dysfunction as occur during massive status epilepticus .
### Output Text:
Both cell elements may suffer in common from metabolic disturbance and neurotransmitter dysfunction as occur during massive status epilepticus . 