title: Technetium labeling of dextran incorporating cysteamine as a ligand.
abstract: BACKGROUND
  Technetium-99m-labeled dextran is a useful imaging agent for procedures such as angiocardiography and lymphoscintigraphy. To improve the availability of 99mTc-labeled dextran, we designed a cysteamine ligand system for dextran labeling.
  
  
  METHODS
  Cysteamine derivatized dextran was synthesized as follows. Dextran was oxidized with sodium periodate, coupled with cysteamine and reduced with sodium borohydride to provide the desired amine ligand. The cysteamine-dextran conjugate was then labeled with reduced 99mTc. Whole-body scintigraphy and biodistribution were examined following injection of the 99mTc-labeled cysteamine-conjugated dextran (99mTc-cysteamine-dextran) in ICR mice. Lymphoscintigraphy was performed after intradermal injection of 99mTc-cysteamine-dextran in SD rats.
  
  
  RESULTS
  The cysteamine-derived dextran was easily labeled with reduced 99mTc in greater than 96% yield. 99mTc-cysteamine-dextran has a higher chelation stability against diethylenetriamine pentaacetic acid (DTPA) than the 99mTc-dextran. Axillary lymph nodes were clearly visible after intradermal injection of 99mTc-cysteamine-dextran in rats.
  
  
  CONCLUSIONS
  These results suggest that 99mTc-cysteamine-dextran is available for lymphoscintigraphy. This methodology could expand the usage of 99mTc-labeled dextran, particularly for diagnostic purposes.
authors.affiliation: Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180, Japan. k-matsu@fukuoka-u.ac.jp
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Matsunaga
authors.forename: Kazumichi
authors.initials: K
authors.lastname: Hara
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imamura
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Fujioka
authors.forename: Jiro
authors.initials: J
authors.lastname: Takata
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Karube
mesh_terms: D000818:Animals; D003543:Cysteamine / Q000737:chemistry / Q000493:pharmacokinetics*; D003911:Dextrans / Q000737:chemistry / Q000493:pharmacokinetics*; D008024:Ligands; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008813:Mice, Inbred ICR; D009928:Organ Specificity; D015609:Organotechnetium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics; D051381:Rats; D014018:Tissue Distribution
chemical_list: D003911:Dextrans; D008024:Ligands; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C034146:technetium Tc 99m dextran; D003543:Cysteamine