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: Thus , MIBG accumulation in the myocardium decreased in an adriamycin dose - dependent manner .
### Output Text:
Thus , <span class="chemical">MIBG</span> accumulation in the myocardium decreased in an <span class="chemical">adriamycin</span> dose - dependent manner . 