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: Superoxide dismutase ( SOD ) or dimethylthiourea ( DMTU ) significantly lessened the GM - induced decrement in CIn .
### Output Text:
<span class="chemical">Superoxide</span> dismutase ( SOD ) or <span class="chemical">dimethylthiourea</span> ( <span class="chemical">DMTU</span> ) significantly lessened the <span class="chemical">GM</span> - induced decrement in CIn . 