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: Cardiac Angiography in Renally Impaired Patients ( CARE ) study : a randomized double - blind trial of contrast - induced nephropathy in patients with chronic kidney disease .
### Output Text:
Cardiac Angiography in Renally Impaired Patients ( CARE ) study : a randomized double - blind trial of contrast - induced nephropathy in patients with chronic kidney disease . 