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 the remaining 12 patients , localised computed tomography of the gall bladder showed that eight had stones with maximum attenuation scores of < 100 Hounsfield units ( values of < 100 HU predict cholesterol rich , dissolvable stones ) .
### Output Text:
In the remaining 12 patients , localised computed tomography of the gall bladder showed that eight had stones with maximum attenuation scores of < 100 Hounsfield units ( values of < 100 HU predict <span class="chemical">cholesterol</span> rich , dissolvable stones ) . 