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: With 2 - week chronic epinephrine infusion , 16 of 30 rats died within 4 days , and severe ischemic lesions and fibrosis of the left ventricles were observed .
### Output Text:
With 2 - week chronic <span class="chemical">epinephrine</span> infusion , 16 of 30 rats died within 4 days , and severe ischemic lesions and fibrosis of the left ventricles were observed . 