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.
Urea is a hot concentrated solution produced by the reaction of ammonia with carbon dioxide. When dissolved with water, this concentrated urea hot-melt liquid becomes an aqueous urea solution or a feedstock for the prilling or granulating process. Prilled urea is used for the technical grade urea market for industrial applications. Prills are small spherical particles.