2390
Although nonsteroidal anti - inflammatory drugs often cause ulcers in the duodenum in humans , the role of cyclooxygenase ( COX ) isoforms in the pathogenesis of duodenal ulcers has not been fully elucidated .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None