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: Desferrioxamine withdrawal resulted in a complete recovery of visual function in 1 patient and partial recovery in 3 , and a complete reversal of hearing loss in 3 patients and partial recovery in 3 .
### Output Text:
<span class="chemical">Desferrioxamine</span> withdrawal resulted in a complete recovery of visual function in 1 patient and partial recovery in 3 , and a complete reversal of hearing loss in 3 patients and partial recovery in 3 . 