alexa Radioimmunoassay for insulin-like growth factor-I: solutions to some potential problems and pitfalls.
Materials Science

Materials Science

Journal of Nanomedicine & Nanotechnology

Author(s): Breier BH, Gallaher BW, Gluckman PD

Abstract Share this page

Abstract This report describes essential requirements for the validation of a radioimmunoassay (RIA) for insulin-like growth factor-I (IGF-I) and presents solutions to some problems and pitfalls commonly observed. The preparation of IGF-I to be used as radioligand or standard has to be selected carefully since some IGF-I preparations are contaminated with variants which demonstrate different potencies for different antisera used in the RIA. Accurate assessment of IGF-I levels in blood plasma requires an efficient extraction method for the IGF-binding proteins (IGFBPs). Extraction methods to remove the influence of IGFBPs in the RIA were compared using blood plasma of considerable differences in IGF-I/IGFBP ratios. Acidification of plasma before column chromatography on Sephadex G-75 (G75) is generally considered to be the most reliable extraction method, but it is very time-consuming. The acid-ethanol extraction (AE) of plasma is not valid in many situations. Non-parallel displacement to the IGF-I standard was observed with AE-extracted plasma samples in the RIA. In addition, a comparison of IGF-I values obtained in the RIA after AE or G75 extraction of fetal ovine plasma has shown no significant correlation. We report an extraction technique based on a modified AE extraction followed by cryo-precipitation (AEC). AEC extraction on blood plasma reduced residual IGFBPs to a level that did not interfere in the assay. Furthermore, AEC-extracted plasma samples showed parallel displacement in the RIA to highly purified preparations of authentic IGF-I. We observed high correlations, with a slope close to unity, of IGF-I values obtained in the RIA using the AEC or G75 extraction for plasma from different species including adult and fetal sheep, rat, mouse and man. The AEC extraction provides a rapid and simple alternative to G75 extraction for blood plasma from a variety of species provided that high-affinity antisera are used for the RIA.
This article was published in J Endocrinol and referenced in Journal of Nanomedicine & Nanotechnology

Relevant Expert PPTs

Recommended Conferences

  • Nano Congress for Next Generation
    August 31-September 01, 2017 Brussels,Belgium
  • Graphene & 2D Materials
    September 14-15, 2017 Edinburgh, Scotland
  • Graphene & 2D Materials
    November 6-7, 2017 Frankfurt, Germany
  • World Congress on Nanoscience and Nano Technology
    October 16-17, 2017 Dubai, UAE
  • World Medical Nanotechnology Congress
    October 18-19, 2017 Osaka, Japan
  • Nanoscienceand Molecular Nanotechnology
    Nov 06-08, 2017 Frankfurt, Germany
Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals
International Conferences 2017-18
Meet Inspiring Speakers and Experts at our 3000+ Global Annual Meetings

Contact Us

© 2008-2017 OMICS International - Open Access Publisher. Best viewed in Mozilla Firefox | Google Chrome | Above IE 7.0 version