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: These results suggest that enhanced prostaglandin synthesis contributes to maintenance of renal function and morphological integrity , and that inhibition of prostaglandin synthesis may lead to pathological renal medullary lesions and deterioration of renal function .
### Output Text:
These results suggest that enhanced <span class="chemical">prostaglandin</span> synthesis contributes to maintenance of renal function and morphological integrity , and that inhibition of <span class="chemical">prostaglandin</span> synthesis may lead to pathological renal medullary lesions and deterioration of renal function . 