Related Experiment Videos
A receptor assay for somatomedin-like activity using multiplication-stimulating activity (MSA) as radioligand
Abstract:
Multiplication-stimulating activity (MSA) in the medium of cultured rat liver cells was purified 120-fold by chromatography on Dowex 50W and Sephadex G 50. MSA was labelled with 125I-iodine and bound to a human placental membrane receptor. An assay for somatomedin-like receptor activity (SmLRA) in unextracted serum was based on the displacement of 125I-MSA from the placental receptor. The mean lambda (precision) was 0.063, sensitivity was less than 0.006 SmLRA units and interassay variation was 18%. The mean (+/- S.D.) SmLRA concentrations in 13 normal subjects, 7 growth hormone deficient patients and 8 patients with active acromegaly were 0.86 +/- 0.19, 0.34 +/- 0.08 and 2.34 +/- 0.82 U/ml, respectively. This assay may have potential clinical application in disorders of growth hormone secretion.
Insights
Researchers developed a new assay to measure somatomedin-like receptor activity (SmLRA) using purified multiplication-stimulating activity (MSA). This assay shows potential for diagnosing growth hormone secretion disorders.
Area of Science:
- Endocrinology
- Biochemistry
Background:
- Multiplication-stimulating activity (MSA) is a growth factor produced by rat liver cells.
- Receptor binding assays are crucial for understanding hormone function and developing diagnostic tools.
Purpose of the Study:
- To purify MSA and develop a novel assay for somatomedin-like receptor activity (SmLRA).
- To evaluate the assay's precision, sensitivity, and interassay variation.
- To measure SmLRA concentrations in normal subjects and patients with growth hormone disorders.
Main Methods:
- Purification of MSA from cultured rat liver cells using chromatography (Dowex 50W, Sephadex G 50).
- Labeling MSA with 125I-iodine and binding it to a human placental membrane receptor.
- Development of a competitive binding assay based on the displacement of 125I-MSA.
Main Results:
- MSA was purified 120-fold.
- The SmLRA assay demonstrated good precision (lambda = 0.063) and sensitivity (< 0.006 SmLRA units).
- Mean SmLRA concentrations differed significantly between normal subjects (0.86 U/ml), growth hormone deficient patients (0.34 U/ml), and acromegaly patients (2.34 U/ml).
Conclusions:
- A sensitive and precise assay for SmLRA has been developed.
- The assay effectively differentiates between normal individuals and those with growth hormone secretion disorders.
- This assay holds potential for clinical applications in diagnosing endocrine conditions related to growth hormone.