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.
Uera Fertilizer. Urea is a white crystalline substance with the chemical formula CO(NH2)2; it is highly water soluble and contains 46% nitrogen. Urea is considered an organic compound because it contains carbon.It was the first organic compound ever synthesized by chemists; this was accomplished in the early 1800s.era Fertilizer. Urea is a white crystalline substance with the chemical formula CO(NH2)2; it is highly water soluble and contains 46% nitrogen. Urea is considered an organic compound because it contains carbon.