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: Pneumonitis , bilateral pleural effusions , echocardiographic evidence of cardiac tamponade , and positive autoantibodies developed in a 43 - year - old man , who was receiving long - term sulfasalazine therapy for chronic ulcerative colitis .
### Output Text:
Pneumonitis , bilateral pleural effusions , echocardiographic evidence of cardiac tamponade , and positive autoantibodies developed in a 43 - year - old man , who was receiving long - term <span class="chemical">sulfasalazine</span> therapy for chronic ulcerative colitis . 