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: HS diet for 4 wk caused a progressive increase in BP , protein and albumin excretion , and glomerular sclerosis in male DS rats , which were attenuated by castration .
### Output Text:
HS diet for 4 wk caused a progressive increase in BP , protein and albumin excretion , and glomerular sclerosis in male DS rats , which were attenuated by castration . 