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: Clinical and experimental studies also suggest that situations causing gallbladder dysfunction , such as fasting , may have a role for the development of pseudolithiasis .
### Output Text:
Clinical and experimental studies also suggest that situations causing gallbladder dysfunction , such as fasting , may have a role for the development of pseudolithiasis . 