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: After 4 - week administration of L - NAME , the systolic blood pressure ( SBP ) increased by 36 % .
### Output Text:
After 4 - week administration of <span class="chemical">L - NAME</span> , the systolic blood pressure ( SBP ) increased by 36 % . 