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: Minor neurological dysfunction , cognitive development , and somatic development at the age of 3 to 7 years after dexamethasone treatment in very - low birth - weight infants .
### Output Text:
Minor neurological dysfunction , cognitive development , and somatic development at the age of 3 to 7 years after <span class="chemical">dexamethasone</span> treatment in very - low birth - weight infants . 