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: High levels of matrix Gla protein are found at sites of artery calcification in rats treated with vitamin D plus Warfarin , and chemical analysis showed that the protein that accumulated was indeed not gamma - carboxylated .
### Output Text:
High levels of matrix Gla protein are found at sites of artery calcification in rats treated with <span class="chemical">vitamin D</span> plus <span class="chemical">Warfarin</span> , and chemical analysis showed that the protein that accumulated was indeed not <span class="chemical">gamma - carboxylated</span> . 