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 this way they obtained appreciable changes in body weight ( increased from 50 to 70 g after forty days at a dose of 5 mg per day of anabolizing agent ) , but most of all they found histological changes due to " regenerative " changes in the muscle tissue , which however maintained its myopathic characteristics in the control animals that were not treated with the anabolizing agent .
### Output Text:
In this way they obtained appreciable changes in body weight ( increased from 50 to 70 g after forty days at a dose of 5 mg per day of anabolizing agent ) , but most of all they found histological changes due to " regenerative " changes in the muscle tissue , which however maintained its myopathic characteristics in the control animals that were not treated with the anabolizing agent . 