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: We studied a thiamine - dependent enzyme , transketolase , from fibroblasts of a diabetic patient who developed Wernicke ' s encephalopathy when treated with tolazamide , in order to delineate if this patient also had transketolase abnormality [ high Km for thiamine pyrophosphate ( TPP ) ] , as previously reported in postalcoholic Wernicke - Korsakoff syndrome .
### Output Text:
We studied a <span class="chemical">thiamine</span> - dependent enzyme , transketolase , from fibroblasts of a diabetic patient who developed Wernicke ' s encephalopathy when treated with <span class="chemical">tolazamide</span> , in order to delineate if this patient also had transketolase abnormality [ high Km for <span class="chemical">thiamine pyrophosphate</span> ( <span class="chemical">TPP</span> ) ] , as previously reported in postalcoholic Wernicke - Korsakoff syndrome . 