Search Results
You are looking at 1 - 2 of 2 items for
- Author: S. Mesiano x
- Refine by access: All content x
Search for other papers by S. Mesiano in
Google Scholar
PubMed
Search for other papers by I. R. Young in
Google Scholar
PubMed
Search for other papers by C. A. Browne in
Google Scholar
PubMed
Search for other papers by G. D. Thorburn in
Google Scholar
PubMed
ABSTRACT
Acid–ethanol precipitation and gel filtration at acidic pH have been widely used to extract circulating binding proteins for insulin-like growth factor (IGF-I and IGF-II) from plasma or serum samples before radioligand assay for the respective IGFs. Gel filtration on Sephadex G-50 at neutral pH of neutralized acid– ethanol extracts of fetal and adult ovine plasma which had been incubated with 125I-labelled IGF-I or 125I-labelled IGF-II revealed that significant amounts of the IGF-binding protein activity survived the acid– ethanol extraction procedure.
Radioimmunoassay for IGF-I in acid–ethanol extracts of plasma samples from fetal, neonatal and adult sheep yielded results which depended upon the method used for separation of the antibody-bound IGF-I tracer from the free IGF-I tracer. Acid gel filtration of ovine fetal and adult plasma was found to remove completely the IGF-binding protein activity. Radioimmunoassay for IGF-I in samples of fetal, neonatal and adult sheep plasma that had undergone acid gel chromatography yielded consistent results for both methods that were used to separate antibody-bound IGF-I tracer from the free tracer.
Radioreceptor assays for IGF-II were similarly highly perturbed by the presence of binding protein in acid–ethanol extracts of ovine fetal and adult plasma. We conclude that acid–ethanol extraction can not be used reliably for the removal of IGF-binding proteins, and that only acid gel filtration is a completely safe and valid method.
J. Endocr. (1988) 119, 453–460
Search for other papers by I. R. Young in
Google Scholar
PubMed
Search for other papers by S. Mesiano in
Google Scholar
PubMed
Search for other papers by R. Hintz in
Google Scholar
PubMed
Search for other papers by D. J. Caddy in
Google Scholar
PubMed
Search for other papers by M. M. Ralph in
Google Scholar
PubMed
Search for other papers by C. A. Browne in
Google Scholar
PubMed
Search for other papers by G. D. Thorburn in
Google Scholar
PubMed
ABSTRACT
Castrated prepubertal lambs were hypophysectomized and then treated with GH and testosterone either alone or in combination over a series of 3-week treatment periods. Hypophysectomy resulted in a rapid reduction in skeletal growth rate which could be reversed by the administration of either GH (4IU three times a week for 3 weeks) or testosterone propionate (10 mg daily for 3 weeks). When GH or testosterone treatment was withdrawn, skeletal growth fell to the post-operative rate. Combined treatment with both GH and testosterone was no more or less effective than either hormone given singly. The order of administration did not have any effect on the growth rate. Circulating concentrations of insulin-like growth factor-I (IGF-I) were reduced by hypophysectomy, but neither GH nor testosterone treatment, alone or in combination, had any effect on IGF-I concentrations. Concentrations of IGF-II rose following hypophysectomy, and again were not affected by any of the hormonal replacement treatments.
In conclusion, both GH and testosterone could stimulate skeletal growth in the hypophysectomized lamb without any alteration of circulating IGF concentrations, and testosterone can clearly stimulate skeletal growth in the complete absence of GH.
Journal of Endocrinology (1989) 121, 563–570
