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 : Most patients with cTnI elevations meet CK - MB criteria for MI , as well as have a high incidence of underlying significant disease .
### Output Text:
CONCLUSIONS : Most patients with cTnI elevations meet CK - MB criteria for MI , as well as have a high incidence of underlying significant disease . 