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 conclusion , lead - induced hypertension in this model was associated with a compensatory upregulation of renal and vascular eNOS and iNOS expression .
### Output Text:
In conclusion , <span class="chemical">lead</span> - induced hypertension in this model was associated with a compensatory upregulation of renal and vascular eNOS and iNOS expression . 