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: Using a mouse model , we tested whether the rapid reversal of anticoagulation using human prothrombin complex concentrate ( PCC ) can reduce hemorrhagic blood volume .
### Output Text:
Using a mouse model , we tested whether the rapid reversal of anticoagulation using human <span class="chemical">prothrombin complex concentrate</span> ( <span class="chemical">PCC</span> ) can reduce hemorrhagic blood volume . 