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: In all of 7 patients examined acutely , gallbladder contractility was inhibited after a single 100 - micrograms injection .
### Output Text:
In all of 7 patients examined acutely , gallbladder contractility was inhibited after a single 100 - micrograms injection . 