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: The ratio of aberrant cardiomyocytes in mice treated with DOX preceded by monoHER and those in mice treated with saline ranged from 1 . 6 to 2 . 8 ( mean 2 . 2 , 95 % CI 1 . 2 - 4 . 1 , P = 0 . 019 ) .
### Output Text:
The ratio of aberrant cardiomyocytes in mice treated with <span class="chemical">DOX</span> preceded by <span class="chemical">monoHER</span> and those in mice treated with saline ranged from 1 . 6 to 2 . 8 ( mean 2 . 2 , 95 % CI 1 . 2 - 4 . 1 , P = 0 . 019 ) . 