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: CONCLUSIONS : In patients with coronary artery disease , dobutamine induced ischaemia results in prolonged reversible left ventricular dysfunction , presumed to be myocardial stunning , similar to that seen after exercise .
### Output Text:
CONCLUSIONS : In patients with coronary artery disease , <span class="chemical">dobutamine</span> induced ischaemia results in prolonged reversible left ventricular dysfunction , presumed to be myocardial stunning , similar to that seen after exercise . 