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: Angiography was performed in 29 of 38 patients who were cTnI - positive , with significant disease present in 25 ( 86 % ) .
### Output Text:
Angiography was performed in 29 of 38 patients who were cTnI - positive , with significant disease present in 25 ( 86 % ) . 