title: A nitrogen balance experiment using simulated urine samples.
abstract: We describe an undergraduate laboratory experiment that combines the advantages of problem-based learning with the need for biochemistry students to become proficient in practical laboratory skills. It also avoids the need to obtain ethical approval for recruiting volunteers and eliminates any possible biosafety issues with the handling and disposal of large amounts of urine. Simulated human urine samples are prepared that contain urea, uric acid, and creatinine at concentrations that represent the levels expected in 2 liters of urine collected over 24 h from subjects on various protein diets or during different physiological states. The students measure the nitrogen-containing compounds in the "urine samples" using specific colorimetric assays and use the data they generate to derive knowledge about nitrogen balance and the excretory metabolism of amino acids.
authors.affiliation: Department of Biochemistry, University of Otago, P. O. Box 56, Dunedin, New Zealand.
authors.forename: Mehri
authors.initials: M
authors.lastname: Sadighi
authors.forename: Nurit
authors.initials: N
authors.lastname: Reichman
authors.forename: Kaye
authors.initials: K
authors.lastname: Wilson
authors.forename: Alan
authors.initials: A
authors.lastname: Carne
authors.forename: Mary P
authors.initials: MP
authors.lastname: Thompson