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: METHODS AND RESULTS : In order to investigate whether the HAART component zidovudine ( 3 ' - azido - 2 ' , 3 ' - deoxythymidine ; AZT ) triggers the Fas - dependent cell - death pathway and cause cytoskeletal disruption in a murine model of DCM , 8 - week - old transgenic ( expressing Fas ligand in the myocardium : FasL Tg ) and non - transgenic ( NTg ) mice received water ad libitum containing different concentrations of AZT ( 0 , 0 . 07 , 0 . 2 , and 0 . 7 mg / ml ) .
### Output Text:
METHODS AND RESULTS : In order to investigate whether the HAART component <span class="chemical">zidovudine</span> ( <span class="chemical">3 ' - azido - 2 ' , 3 ' - deoxythymidine</span> ; <span class="chemical">AZT</span> ) triggers the Fas - dependent cell - death pathway and cause cytoskeletal disruption in a murine model of DCM , 8 - week - old transgenic ( expressing Fas ligand in the myocardium : FasL Tg ) and non - transgenic ( NTg ) mice received water ad libitum containing different concentrations of <span class="chemical">AZT</span> ( 0 , 0 . 07 , 0 . 2 , and 0 . 7 mg / ml ) . 