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: METHODS : All PD patients in the Amiens area treated with pergolide were invited to attend a cardiologic assessment including transthoracic echocardiography .
### Output Text:
METHODS : All PD patients in the Amiens area treated with <span class="chemical">pergolide</span> were invited to attend a cardiologic assessment including transthoracic echocardiography . 