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: The hearts without coronary artery disease ( average ejection fraction of this group 62 % + / - 10 % ) had a VIP concentration of 14 . 1 + / - 7 . 9 pg / mg protein , and this was greater than in hearts of the patients with coronary disease and the hearts of patients receiving a transplant ( P less than 0 . 05 ) .
### Output Text:
The hearts without coronary artery disease ( average ejection fraction of this group 62 % + / - 10 % ) had a VIP concentration of 14 . 1 + / - 7 . 9 pg / mg protein , and this was greater than in hearts of the patients with coronary disease and the hearts of patients receiving a transplant ( P less than 0 . 05 ) . 