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: GLS ( - 18 . 48 + 1 . 72 % vs . - 15 . 96 + 1 . 6 % ) , GCS ( - 20 . 93 + 2 . 86 % vs . - 19 . 20 + 3 . 21 % ) , and GRS ( 39 . 23 + 6 . 44 % vs . 34 . 98 + 6 . 2 % ) were markedly reduced and cTnT was elevated from 0 . 0010 + 0 . 0020 to 0 . 0073 + 0 . 0038 ng / mL ( P all < 0 . 01 ) at the completion of chemotherapy compared with baseline values .
### Output Text:
GLS ( - 18 . 48 + 1 . 72 % vs . - 15 . 96 + 1 . 6 % ) , GCS ( - 20 . 93 + 2 . 86 % vs . - 19 . 20 + 3 . 21 % ) , and GRS ( 39 . 23 + 6 . 44 % vs . 34 . 98 + 6 . 2 % ) were markedly reduced and cTnT was elevated from 0 . 0010 + 0 . 0020 to 0 . 0073 + 0 . 0038 ng / mL ( P all < 0 . 01 ) at the completion of chemotherapy compared with baseline values . 