Those originally employed were based either on the fusion of the PCE to a tumour specific antibody (Antibody-Directed Prodrug Therapy, ADEPT) or on the delivery of the gene encoding the PCE using viral or non-viral vectors (Gene-Directed Enzyme Prodrug Therapy, GDEPT).
Urea is widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry. Friedrich WÃ¶hler's discovery in 1828 that urea can be produced from inorganic starting materials was an important conceptual milestone in chemistry.
Commercial Production: Urea is a nitrogen-containing chemical product which is produced in excess of 140,000,000 tons per year worldwide, of which more than 90% of world production is destined for use as a fertilizer. Urea is produced commercially from synthetic ammonia and carbon dioxide.