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: This study investigated the expression of nuclear factor - kappaB ( NF - kappaB ) , mitogen - activated protein ( MAP ) kinases and macrophages in the renal cortex and structural and functional renal changes of rats treated with gentamicin or gentamicin + pyrrolidine dithiocarbamate ( PDTC ) , an NF - kappaB inhibitor .
### Output Text:
This study investigated the expression of nuclear factor - kappaB ( NF - kappaB ) , mitogen - activated protein ( MAP ) kinases and macrophages in the renal cortex and structural and functional renal changes of rats treated with <span class="chemical">gentamicin</span> or <span class="chemical">gentamicin</span> + <span class="chemical">pyrrolidine dithiocarbamate</span> ( <span class="chemical">PDTC</span> ) , an NF - kappaB inhibitor . 