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 rise in forearm vascular resistance accompanying intra - arterial norepinephrine ( 25 , 50 , and 100 ng / min ) was also significantly greater after hydrocortisone , increasing from an average of 14 . 9 + / - 2 . 4 R units before treatment to 35 . 1 + / - 5 . 5 R units after hydrocortisone ( SED + / - 6 . 0 , p less than 0 . 05 ) .
### Output Text:
The rise in forearm vascular resistance accompanying intra - arterial <span class="chemical">norepinephrine</span> ( 25 , 50 , and 100 ng / min ) was also significantly greater after <span class="chemical">hydrocortisone</span> , increasing from an average of 14 . 9 + / - 2 . 4 R units before treatment to 35 . 1 + / - 5 . 5 R units after <span class="chemical">hydrocortisone</span> ( SED + / - 6 . 0 , p less than 0 . 05 ) . 