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: EEG undertaken during inpatient stay showed changes consistent with encephalopathy , and low titre N - methyl - D - aspartate ( NMDA ) receptor antibodies were present in this patient .
### Output Text:
EEG undertaken during inpatient stay showed changes consistent with encephalopathy , and low titre <span class="chemical">N - methyl - D - aspartate</span> ( <span class="chemical">NMDA</span> ) receptor antibodies were present in this patient . 