Isolation of a Somatomedin-Binding Protein from Preterm Amniotic Fluid. Development of a Radioimmunoassay*

Drop, Stenvert L. S.; Kortleve, D. J.; Guyda, H.

doi:10.1210/jcem-59-5-899

Cited by 128 publications

(47 citation statements)

References 84 publications

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“…Our IGF-BP25 RIA is similar to that developed in other laboratories, and we have found that levels in normal nonfasting children and adults (Lee PDK, Powell DR, unpublished data) are comparable to levels reported by others (22,24,25), IGF-BP25 levels for large groups of fasting children have not been published. To avoid the reported diurnal variation of circulating IGF-BP25 levels (25), all samples used in the study and control populations were collected in the morning after an overnight fast.…”

Section: Discussionsupporting

confidence: 79%

IGF Binding Proteins in Growth-Retarded Children with Chronic Renal Failure

et al. 1989

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ABSTRACT. Changes in the normal hormonal regulation of linear growth which lead to growth failure in children with chronic renal failure (CRF) are not well understood. Previous studies indicate that serum levels of growth hormone and IGF-I and I1 are normal or elevated in this population; and that serum levels of poorly defined inhibitors of IGF action are increased. Using a recently developed RIA for the 25-kD IGF-binding protein (IGF-BP25), we report significant elevations of this protein in children with CRF when compared to age-and sex-matched controls. IGF-BP25 levels correlate positively with IGF-binding activity in both populations, indicating that the RIA reflects levels of bioactive protein. Although the variation of serum IGF-BP25 with chronologic age and IGF levels are preserved in CRF, the quantitative interrelationships are disrupted. Levels of the 53-kD IGF-binding protein, an IGFbinding protein derived from the high mol wt IGF complex, were also found to be elevated in the CRF population and, unlike in the control population, did not vary with age or IGF levels. IGF-BP25 has been shown to inhibit IGF mitogenic action in vitro. Our finding of elevated levels of IGF-BP25 in children with CRF suggests that this protein may play a role in the growth retardation of pediatric chronic renal failure. The significance of the elevated IGF-BP53 levels in CRF remains uncertain. (Pediatr Res 26:308-315, 1989)

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Section: Discussionsupporting

confidence: 79%

IGF Binding Proteins in Growth-Retarded Children with Chronic Renal Failure

et al. 1989

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“…Assuming that amniotic fluid IGF-I is of fetal origin, then the lack of responsiveness of IGF-I to acute maternal substrate deprivation may reflect a pool that is slowly responsive to acute perturbations of fetal nutritional status. Alternatively, it may be that G-50 acid chromatography does not adequately separate IGF-I from the amniotic fluid binding protein, and thus does not accurately reflect the state of IGF-I in the amniotic fluid compartment under conditions of suboptimal nutrition (20,21).…”

Section: Resultsmentioning

confidence: 99%

Insulin-Like Growth Factor I in Substrate-Deprived, Growth-Retarded Fetal Rats

1991

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ABSTRACF. Plasma, amniotic fluid, and tissue concentra-Control animals were allowed free access to both food and water. tions of IGF-I were examined in nutritionally deprived, Sampling was performed on d 2 1 in all animals, after intraperigrowth-retarded fetal rats to determine whether IGF-I toneal pentobarbital (45 mg/kg) administration. Midline lapaconcentration serves as a marker for nutritional status. rotomy incision was used to expose the uterine horns. Fetuses in Growth retardation was induced by 72 h of maternal fast-each horn were counted, and the two inferior fetuses of each ing. Twenty-three control and 17 growth-retarded fetuses horn were sampled to match the control and test group with were individually analyzed and compared. Plasma IGF-I regard to intrauterine location. A maximum of four fetuses per concentrations were significantly lower in test compared dam were analyzed to insure matching of uterine location bewith control animals (test 56.8 f 14.9, control 87.4 f 17.5 tween groups and to minimize any metabolic impact of the ng/mL, p < 0.01). Amniotic fluid IGF-I concentrations surgical procedure. Only those fetuses in whom results from all were not different (test 14.0 f 8.7, control 12.2 f 2.6 ng/ specimens were available were included in the analyses. The mL). IGF-I concentrations obtained from both placental sampling sequence was initiated by the removal of amniotic fluid and hepatic tissues were lower in test compared with with a 19-or 20-gauge 1-mL syringe. The fetus was then removed control animals [placenta: test 293 f 25 versus control 655 from its location in the uterine horn, and an axillary cutdown f 114 ng/g (p < 0.001); hepatic: test 173 k 38 versus was performed (15). Fetal blood was collected by heparinized control 230 f 51 ng/g ( p < 0.01)]. Reductions in fetal, capillary tube, placed on ice, and centrifuged for 15 min at 12 placental, and hepatic weights in test animals were more 000 X g. The fetus was separated from the placenta, and the closely related to changes in placental IGF-I concentration fetus, placenta, and then fetal liver were weighed. The placenta than to either plasma or hepatic IGF-I concentrations. We and liver were quickfrozen in liquid nitrogen. All samples were conclude that fetal plasma IGF-I is a valuable marker for stored at -80°C until analysis. After fetal sampling, a maternal intrauterine substrate deprivation and that the growth-venous plasma sample was obtained from the inferior vena cava retarded rat fetus is accurately identified and specifically just below the renal vein. Euthanasia was performed by means characterized by a low placental concentration of extract-of exsanguination after all samples had been obtained. Individual Analyses. IGF-I concentrations in maternal and fetal plasma and amniotic fluid were determined by RIA [National Institute Circulating concentrations of IGF-I are influenced by both of Diabetes and Digestive and Kidney Diseases somatomedin-C growth hormone and nutritional status (1-10). Although the antiserum (polyclonal) cod...

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“…wt IGF-BP isolated from human amniotic fluid was raised and purified as described previously (Drop et al, 1984a). The antibody preparation was depleted for Escherichia coli and Xgtl 1 proteins and by incubation with nitrocellulose filters that had been lifted from confluent lysis plates of E.coli Y1090/Xgtl 1, induced with10 mM isopropyl,B-d-thiogalactopyranoside (IPTG).…”

Section: Methodsmentioning

confidence: 99%

“…wt IGF-BP by proteolytic processing . The NH2-terminal amino acids of the 30-35-kd BPs derived from amniotic fluid, human serum and the HEPG2 cell line are completely homologous, suggesting that these proteins are in fact identical (Drop et al, 1984a;Povoa et al, 1985). Recently, another 35-kd IGF-BP has been isolated from soluble extracts of term human placental/fetal membranes .…”

Section: Introductionmentioning

confidence: 99%

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Isolation and characterization of a cDNA encoding the low molecular weight insulin-like growth factor binding protein (IBP-1).

et al. 1988

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IGF‐I and IGF‐II are growth‐stimulating peptides with strong mitogenic properties. These polypeptide growth factors circulate in serum bound to specific binding proteins. We report the cloning and complete sequence of a cDNA encoding a low mol. wt IGF‐binding protein from a human placenta cDNA library. We propose the designation IGF‐binding protein 1 (IBP‐1) for the gene and corresponding protein. Expression of the cDNA encoding IBP‐1 in COS cells resulted in the synthesis of a 30‐kd protein which binds IGF‐I and is immunologically indistinguishable from the IGF‐binding protein isolated from amniotic fluid or human serum. Northern blotting analysis demonstrated that expression of the IBP‐1 gene is highly tissue specific and limited to placental membranes and fetal liver suggesting a rigid control. The IBP‐1 gene is a single copy gene, located on chromosome 7. The results obtained suggest that most, if not all, lower mol. wt IGF‐binding proteins originate from this gene.

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Isolation of a Somatomedin-Binding Protein from Preterm Amniotic Fluid. Development of a Radioimmunoassay*

Cited by 128 publications

References 84 publications

IGF Binding Proteins in Growth-Retarded Children with Chronic Renal Failure

IGF Binding Proteins in Growth-Retarded Children with Chronic Renal Failure

Insulin-Like Growth Factor I in Substrate-Deprived, Growth-Retarded Fetal Rats

Isolation and characterization of a cDNA encoding the low molecular weight insulin-like growth factor binding protein (IBP-1).

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