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: Pulmonary edema and shock after high - dose aracytine - C for lymphoma ; possible role of TNF - alpha and PAF .
### Output Text:
Pulmonary edema and shock after high - dose <span class="chemical">aracytine - C</span> for lymphoma ; possible role of TNF - alpha and PAF . 