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: Histologic changes were found in rat kidneys after administration of MTX , CY and NG , while no such change was observed after 5 - FU and joint administration of MTX + 5 - FU + CY compared to controls .
### Output Text:
Histologic changes were found in rat kidneys after administration of <span class="chemical">MTX</span> , <span class="chemical">CY</span> and <span class="chemical">NG</span> , while no such change was observed after <span class="chemical">5 - FU</span> and joint administration of <span class="chemical">MTX</span> + <span class="chemical">5 - FU</span> + <span class="chemical">CY</span> compared to controls . 