2273
Platelet activating factor was given in six doses at 15 minute intervals and airway response measured as change in partial expiratory flow at 30 % of vital capacity ( Vp30 ) .
 Platelet activating factor
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 Platelet activating factor