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: Seventeen renal patients received azathioprine ( Aza ) and prednisone as part of a randomized trial of immunosuppression with 21 cyclosporine - and - prednisone - treated renal transplant patients .
### Output Text:
Seventeen renal patients received <span class="chemical">azathioprine</span> ( <span class="chemical">Aza</span> ) and <span class="chemical">prednisone</span> as part of a randomized trial of immunosuppression with 21 <span class="chemical">cyclosporine</span> - and - <span class="chemical">prednisone</span> - treated renal transplant patients . 