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 November 2002 , a meeting was held in Florence , bringing together a number of experts in various fields , including rheumatology , cardiology , neurology , pharmacology and transplantation medicine .
### Output Text:
In November 2002 , a meeting was held in Florence , bringing together a number of experts in various fields , including rheumatology , cardiology , neurology , pharmacology and transplantation medicine . 