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: NIMO attenuated the disruption in consolidation of long - term memory caused by NTG but did not improve latency in the absence of hypotension .
### Output Text:
<span class="chemical">NIMO</span> attenuated the disruption in consolidation of long - term memory caused by <span class="chemical">NTG</span> but did not improve latency in the absence of hypotension . 