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: In mice rendered anemic and leukopenic by the administration of AZT for 28 days in drinking water ( 1 . 5 mg / mL ) , the continued administration of AZT plus daily BAU ( 300 mg / kg , orally ) partially reversed AZT - induced anemia and leukopenia ( P less than . 05 ) , increased peripheral reticulocytes ( to 4 . 9 % , P less than . 01 ) , increased cellularity in the marrow , and improved megaloblastosis .
### Output Text:
In mice rendered anemic and leukopenic by the administration of <span class="chemical">AZT</span> for 28 days in drinking water ( 1 . 5 mg / mL ) , the continued administration of <span class="chemical">AZT</span> plus daily <span class="chemical">BAU</span> ( 300 mg / kg , orally ) partially reversed <span class="chemical">AZT</span> - induced anemia and leukopenia ( P less than . 05 ) , increased peripheral reticulocytes ( to 4 . 9 % , P less than . 01 ) , increased cellularity in the marrow , and improved megaloblastosis . 