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Insulin-Like Growth Factors and Insulin-Like Growth Factor Binding Proteins in Porcine Serum and Milk throughout Lactation

Insulin-Like Growth Factors and Insulin-Like Growth Factor Binding Proteins in Porcine Serum and... ABSTRACT: IGF-I, IGF-II, and IGF binding proteins (IGFBP) were characterized in porcine serum, colostrum, and milk on d 1–28 postpartum. IGF-I and -II were measured by heterologous RIA. Scrum IGFBP were characterized by Western ligand blotting and milk IGF binding activity by [125I]-IGF binding assay. IGF-II accounted for 70–85% of serum IGF and rose 2-fold between d 1 and d 28. Serum IGF-I was unaffected by duration of lactation. Milk IGF-II concentrations were higher than IGF-I concentrations on d 1–7 postpartum. After d 10, milk IGF-I and IGF-II contents were not significantly different. Serum contained IGFBP with M, of 43, 39, 34, 28, and 24 kD. Over the course of lactation, the 43− and 39-kD bands increased, the 24-kD band decreased, and the 34− and 28-kD bands were unchanged. Milk IGF binding activity increased between d 1 (28%) and d 3 (44%), then declined until d 28 (7%). Serum and milk were separated by isoelectric focusing into 20 fractions, across a gradient from pH 3 to 10, that were screened for IGFBP by Western ligand blotting. Milk contained six IGFBP of similar Mr as serum IGFBP; however, the relative amounts of the IGFBP and their apparent isoelectric points differed. In conclusion, porcine milk contains both IGF-I and -II, with IGF-II predominating. Several IGFBP with similar Mr as those found in serum are present in milk. IGF peptide concentrations were highest in prepartum secretions and colostrum, whereas IGF binding activity peaked on d 4 of lactation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Pediatric Research Springer Journals

Insulin-Like Growth Factors and Insulin-Like Growth Factor Binding Proteins in Porcine Serum and Milk throughout Lactation

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References (19)

Publisher
Springer Journals
Copyright
Copyright © 1994 by International Pediatrics Research Foundation, Inc.
Subject
Medicine & Public Health; Medicine/Public Health, general; Pediatrics; Pediatric Surgery
ISSN
0031-3998
eISSN
1530-0447
DOI
10.1203/00006450-199408000-00005
Publisher site
See Article on Publisher Site

Abstract

ABSTRACT: IGF-I, IGF-II, and IGF binding proteins (IGFBP) were characterized in porcine serum, colostrum, and milk on d 1–28 postpartum. IGF-I and -II were measured by heterologous RIA. Scrum IGFBP were characterized by Western ligand blotting and milk IGF binding activity by [125I]-IGF binding assay. IGF-II accounted for 70–85% of serum IGF and rose 2-fold between d 1 and d 28. Serum IGF-I was unaffected by duration of lactation. Milk IGF-II concentrations were higher than IGF-I concentrations on d 1–7 postpartum. After d 10, milk IGF-I and IGF-II contents were not significantly different. Serum contained IGFBP with M, of 43, 39, 34, 28, and 24 kD. Over the course of lactation, the 43− and 39-kD bands increased, the 24-kD band decreased, and the 34− and 28-kD bands were unchanged. Milk IGF binding activity increased between d 1 (28%) and d 3 (44%), then declined until d 28 (7%). Serum and milk were separated by isoelectric focusing into 20 fractions, across a gradient from pH 3 to 10, that were screened for IGFBP by Western ligand blotting. Milk contained six IGFBP of similar Mr as serum IGFBP; however, the relative amounts of the IGFBP and their apparent isoelectric points differed. In conclusion, porcine milk contains both IGF-I and -II, with IGF-II predominating. Several IGFBP with similar Mr as those found in serum are present in milk. IGF peptide concentrations were highest in prepartum secretions and colostrum, whereas IGF binding activity peaked on d 4 of lactation.

Journal

Pediatric ResearchSpringer Journals

Published: Aug 1, 1994

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