the present invention is directed to a novel imidazo pyridinium molecule composed of a lysine and an arginine residue crosslinked with a pentose sugar . the novel imidazo pyridinium compound , referred to as &# 34 ; pentosidine &# 34 ;, was isolated from proteineous tissue undergoing advanced glycosylation and is believed to be one of the principal products involved in the nonenzymatic browning and / or aging of proteins . assaying for the pentosidine molecule makes it possible to assess the degree of aging of proteins in vivo as mediated by pentose induced crosslinking and modulated by disease such as diabetes and nephropathy . in addition , the pentosidine molecule may be utilized through the production of monoclonal antibodies thereto and / or the preparation of test kits , etc . for diagnostic , as well as therapeutic purposes .