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: One day postlesion , the resting mean arterial pressure was significantly decreased in lesioned rats when compared with sham rats ( 100 + / - 7 versus 173 + / - 4 mm Hg , p less than 0 . 05 ) .
### Output Text:
One day postlesion , the resting mean arterial pressure was significantly decreased in lesioned rats when compared with sham rats ( 100 + / - 7 versus 173 + / - 4 mm Hg , p less than 0 . 05 ) . 