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: Neither L - arginine transport into mononuclear cells ( placebo vs active , 26 . 3 + / - 3 . 6 vs 29 . 0 + / - 2 . 1 pmol / 10 000 cells per 5 minutes , respectively , at an l - arginine concentration of 300 micromol / L ) nor L - arginine extraction in the forearm ( at 80 minutes , placebo vs active , 1 868 904 + / - 434 962 vs 2 013 910 + / - 770 619 disintegrations per minute ) was affected by cortisol treatment ; ie , that L - arginine uptake is not affected by short - term cortisol treatment .
### Output Text:
Neither <span class="chemical">L - arginine</span> transport into mononuclear cells ( placebo vs active , 26 . 3 + / - 3 . 6 vs 29 . 0 + / - 2 . 1 pmol / 10 000 cells per 5 minutes , respectively , at an <span class="chemical">l - arginine</span> concentration of 300 micromol / L ) nor <span class="chemical">L - arginine</span> extraction in the forearm ( at 80 minutes , placebo vs active , 1 868 904 + / - 434 962 vs 2 013 910 + / - 770 619 disintegrations per minute ) was affected by <span class="chemical">cortisol</span> treatment ; ie , that <span class="chemical">L - arginine</span> uptake is not affected by short - term <span class="chemical">cortisol</span> treatment . 