Vera D R
Department of Radiology, University of California, Davis, Medical Center, Sacramento, California 95817.
J Nucl Med. 1992 Jun;33(6):1160-6.
Galactosyl-neoglycoalbumin (NGA) is a synthetic ligand to the hepatocyte-specific receptor, hepatic binding protein. In-vitro and in-vivo characterization of a chelation-based derivative of NGA, deferoxamine-galactosyl-neoglycoalbumin (DF-NGA), is described. A two-step glutaraldehyde method was used to covalently couple deferoxamine (DF) to NGA. Products with an average DF-to-NGA ratio of less than 2 contained less than 3% polymeric DF-NGA. All products retained the chelator after 12 mo of storage at 4 degrees C. Gallium labeling of DF-NGA-41 (41 galactose units per HSA) with an average of 1.1 DF per NGA was quantitative within 15 min after the addition of 67Ga-citrate. The labeled product was stable for at least 24 hr. Scatchard and reverse-binding assays of 67Ga-DF-NGA-41 revealed a forward binding rate constant kb similar to that of 125I-NGA-44. The %ID of 67Ga-DF-NGA-41 in rabbit liver was approximately 90% at 10 min after injection of 1.2 x 10(-9) mole DF-NGA per kilogram of body weight. This value decreased to 40% at a scaled molar dose of 1.2 x 10(-7) mol/kg. Biodistribution data of 67Ga-DF-NGA in rabbits was similar to 99mTc-NGA. High tissue specificity and facile labeling will make 68Ga-labeled neoglycoalbumin an ideal agent for regional measurements of receptor biochemistry in the investigational and clinical setting.
半乳糖基-新糖白蛋白（NGA）是肝细胞特异性受体——肝结合蛋白的一种合成配体。本文描述了NGA的一种基于螯合作用的衍生物——去铁胺-半乳糖基-新糖白蛋白（DF-NGA）的体外和体内特性。采用两步戊二醛法将去铁胺（DF）与NGA共价偶联。平均DF与NGA比例小于2的产物中聚合DF-NGA含量低于3%。所有产物在4℃储存12个月后仍保留螯合剂。用平均每个NGA含1.1个DF的DF-NGA-41（每HSA含41个半乳糖单位）标记镓，在加入枸橼酸镓后15分钟内定量完成。标记产物至少稳定24小时。对67Ga-DF-NGA-41进行Scatchard和反向结合分析，结果显示其正向结合速率常数kb与125I-NGA-44相似。每千克体重注射1.2×10⁻⁹摩尔DF-NGA后10分钟，兔肝脏中67Ga-DF-NGA-41的摄取率约为90%。在按比例扩大至1.2×10⁻⁷摩尔/千克的摩尔剂量时，该值降至40%。67Ga-DF-NGA在兔体内的生物分布数据与99mTc-NGA相似。高组织特异性和易于标记将使68Ga标记的新糖白蛋白成为研究和临床环境中受体生物化学区域测量的理想试剂。
