Furfural: exogenous precursor of certain urinary furans and possible toxicologic agent in humans.

desickling action of urea is a concentration-dependent event. McCurdy and Mahmood (5) were successful in 14 trials out of 24 with i. v. urea, even though they also used urea at blood levels below those specified. Furthermore, they suggested that their failures might be dose-related. I am surprised that they did so well for the i. v. modality, since they used urea only at 70 to 120 mg/100 ml instead of the specified 150 to 200 mg/100 ml. Aside from our published reports, there are thus six (5-10) other independent groups who have had successful experiences (though our protocol was not completely followed) with urea therapy, and two groups (3, 4) (using entirely inadequate quantities of urea) who have had complete failures.