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To elucidate the underlying mechanisms associated with ketamine - induced neuronal toxicity and search for approaches or agents to prevent ketamine ' s adverse effects on the developing brain , a primary nerve cell culture system was utilized .
 Chemical: ketamine; Chemical: ketamine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: ketamine; Chemical: ketamine