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: Prednisolone - induced muscle dysfunction is caused more by atrophy than by altered acetylcholine receptor expression .
### Output Text:
<span class="chemical">Prednisolone</span> - induced muscle dysfunction is caused more by atrophy than by altered <span class="chemical">acetylcholine</span> receptor expression . 