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: There was a remarkable reduction in total cholesterol level as well , to the extent of 23 % in young and 21 % in aged animals with this dose of DCE .
### Output Text:
There was a remarkable reduction in total <span class="chemical">cholesterol</span> level as well , to the extent of 23 % in young and 21 % in aged animals with this dose of <span class="chemical">DCE</span> . 