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: Neonatal cardiomyocytes were isolated from Sprague - Dawley rat hearts and randomly divided into controls , an adriamycin - treated group , and a 3MA plus adriamycin - treated group .
### Output Text:
Neonatal cardiomyocytes were isolated from Sprague - Dawley rat hearts and randomly divided into controls , an <span class="chemical">adriamycin</span> - treated group , and a <span class="chemical">3MA</span> plus <span class="chemical">adriamycin</span> - treated group . 