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: Toxic peripheral neuropathy is still a significant limiting factor for chemotherapy with paclitaxel ( PAC ) , although glutamate and its closely related amino acid glutamine were claimed to ameliorate PAC neurotoxicity .
### Output Text:
Toxic peripheral neuropathy is still a significant limiting factor for chemotherapy with <span class="chemical">paclitaxel</span> ( <span class="chemical">PAC</span> ) , although <span class="chemical">glutamate</span> and its closely related <span class="chemical">amino acid</span> <span class="chemical">glutamine</span> were claimed to ameliorate <span class="chemical">PAC</span> neurotoxicity . 