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 found significant positive correlations between the preoperative levodopa responsiveness of motor signs and the levodopa responsiveness of scores in timed tests ( Core Assessment Program for Intracerebral Transplantations ) in the contralateral limbs and the improvement in these scores after surgery , whereas there was no correlation with the improvement in LID .
### Output Text:
We found significant positive correlations between the preoperative <span class="chemical">levodopa</span> responsiveness of motor signs and the <span class="chemical">levodopa</span> responsiveness of scores in timed tests ( Core Assessment Program for Intracerebral Transplantations ) in the contralateral limbs and the improvement in these scores after surgery , whereas there was no correlation with the improvement in LID . 