21629
These advances have greatly increased our understanding of the physiological and pathophysiological functions of P2X and P2Y receptors , but investigation of the clinical usefulness of selective ligands is at an early stage .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None