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: In contrast , AZT - treated FasL Tg mice developed cardiac dilation and depressed cardiac function in a dose - dependent manner , with concomitant inflammatory infiltration of both ventricles .
### Output Text:
In contrast , <span class="chemical">AZT</span> - treated FasL Tg mice developed cardiac dilation and depressed cardiac function in a dose - dependent manner , with concomitant inflammatory infiltration of both ventricles . 