title: Mutagenicity induced by lyophilization or storage of urine from isoniazid-treated rats.
abstract: Urine collected during 24 h after treatment of rats with 90--550 mg/kg isonicotinic acid hydrazide (isoniazid, INH) was after lyophilization, mutagenic for Salmonella typhimurium TA1535. Urine collected directly from bladders of INH-treated rats was not mutagenic, and solutions of INH in water or urine became mutagenic only after lyophilization. In the absence of lyophilization, sterile urine from INH-treated rats became mutagenic after 8--14 days' storage at room temperature.
mesh_terms: D005612:Freeze Drying; D005821:Genetic Techniques; D007538:Isoniazid / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000378:metabolism; D009153:Mutagens; D012486:Salmonella typhimurium / Q000235:genetics; D014556:Urine / Q000378:metabolism*
chemical_list: D009153:Mutagens; D007538:Isoniazid