Nonsuppressible Insulin-Like Activity (NSILA). I. Development of New Sensitive Competitive Protein-Binding Assay for Determination of Serum Levels*

Schalch, Don S.; Heinrich, U.; Koch, Janet G.; Johnson, Carolyn J.; Schlueter, Robert J.

doi:10.1210/jcem-46-4-664

Cited by 50 publications

(9 citation statements)

References 17 publications

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“…- normal sera than had been achieved with assays using human serum BPs [21,22] and also, our results were very similar to those obtained with the SM-C/IGF-I R1A [14], Moreover, when we used BPs extracted from either human or rat serum, the differentia tion between acromegalic and normal serum was far less clear-cut (table I). From these findings we could infer the following: (1) that the BPs produced by rat liver recognized IGF-I better than did the serum BPs; (2) that the preferential affinity was not specieslinked, since human and rat serum BPs gave similar results, and (3) that different forms of BP must exist with different affinities for IGF-I and IGF-II, which are produced in dif ferent quantities either by the same cells or by different cells.…”

Section: Introductionsupporting

confidence: 88%

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

et al. 1986

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The insulin-like growth factor (IGF)-binding proteins present in the human serum and various biological media have been characterized by several methods: gel filtration, sucrose gradient sedimentation, polyacrylamide gel electrophoresis and chromatofocusing. Several forms have been identified with molecular weights of ∼ 42,000, 39,000, 34,000, 30,000 and 24,000 daltons. Results of competitive binding studies suggest that the different forms of binding proteins have different affinities for IGF-I and IGF-II. The influence of various hormones and pathophysiological conditions on the biosynthesis of the binding proteins has been investigated.

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Section: Introductionsupporting

confidence: 88%

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

et al. 1986

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“…For monitoring isolation a competitive protein binding assay described by Schalch et al (1978) was adopted. The tracer was prepared from a highly purified IGF-I-like peptide corresponding to Sm III previously isolated from hu¬ man plasma (Blum et al 1984) using the chloramine method.…”

Section: Assaysmentioning

confidence: 99%

Isolation and partial characterization of six somatomedin-like peptides from human plasma Cohn fraction IV

Blum

Ranke

Bierich

1986

Acta Endocrinologica

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Six somatomedin-like peptides were purified from human plasma Cohn fraction IV by a six-step procedure which included ethanol precipitation, reversed-phase extraction, gel filtration, chromatofocusing and reversed-phase high pressure liquid chromatography (HPLC). Purification was monitored with a competitive protein binding assay using a crude preparations of somatomedin carrier protein. The peptides isolated were homogeneous by reversed-phase HPLC and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Their apparent isoelectric points determined by chromatofocusing were 9.2 (Sm I), (Sm II), 8.2 (Sm III), 6.7 (Sm IV), 6.3 (Sm V), and 6.15 (Sm VI). SDS-PAGE under reducing conditions revealed that they are composed of a single peptide chain with apparent molecular weights of 6800 for Sm I, II and IV and 6400 for Sm III, V, and VI.They were equally potent in the porcine costal cartilage in vitro bioassay. The basic peptides (Sm I\p=n-\III) were significantly more active in radioimmunoassays for somatomedin C (SmC) and insulin-like growth factor I C-peptide (IGF-I (30\p=n-\41)),while only the slightly acidic peptides were active in a radioimmunoassay for insulin\x=req-\ like growth factor II C-peptide (IGF-II (33\p=n-\40)). When receptor binding was tested with human placental cell membranes and Sm III as tracer, the basic peptides were significantly more potent than Sm IV\p=n-\VI.With rat liver cell membranes and Sm V as tracer the slightly acidic peptides were more potent. These findings suggest 1) that human plasma may contain other somatomedin-like peptides besides the major components IGF-I/SmC and IGF-II, and 2) that the basic peptides are structurally related to IGF-I/SmC and the slightly acidic peptides are related to IGF-II.

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“…We measured serum total IGF (IGF-I and -II) by the competitive protein binding assay of Schalch et al (19), and IGF-I by the RIA method of Furlanetto et al (20). The IGF preparations used in these assays (3.8 mU/mg IGF-I and -II for standards and 200 mU/mg IGF-I for iodination) were generously provided by Prof. R. E. Humbel, and the IGF-I/Sm-C antiserum was a gift from the National Hormone and Pituitary Program and Drs.…”

Section: Assaysmentioning

confidence: 99%

Protein Utilization in Growth: Effect of Lysine Deficiency on Serum Growth Hormone, Somatomedins, Insulin, Total Thyroxine (T₄) and Triiodothyronine, Free T₄Index, and Total Corticosterone

Cree

Schalch

1985

Endocrinology

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We have studied the effect of a lysine-deficient diet on the growth of young rats and on serum levels of GH, somatomedins [insulin-like growth factors (IGFs) I and II], insulin, total T4 and T3, free T4 index, and total corticosterone. Rats eating a wheat gluten diet consumed about one third as much lysine as controls eating an isocaloric and isonitrogenous casein diet and grew at approximately 56% of the control rate. The mean (+/- SEM) GH level in the experimental group (68 +/- 9 ng/ml) was significantly lower (P less than 0.01) than that in the controls (106 +/- 17 ng/ml), but was not correlated with age or body weight and was only weakly correlated with total IGF. In contrast, total IGF and IGF-I were significantly correlated with age and body weight (r = 0.86 and r = 0.84, respectively; P less than 0.01). The levels of these somatomedins in the wheat gluten-fed animals were consistently and significantly lower than those in their age-matched controls, but not significantly different from those in their weight-matched controls, throughout the study. Serum total T4 and T3 (but not the free T4 index) and corticosterone were significantly elevated in the experimental rats, perhaps representing a serum binding globulin adaptation to lysine deficiency that is not clearly understood. In this study, we have compromised the ability of growing rats to use dietary protein anabolically to examine the nutritional effects of qualitative protein deficiency on growth and the growth-promoting endocrine system.

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Nonsuppressible Insulin-Like Activity (NSILA). I. Development of New Sensitive Competitive Protein-Binding Assay for Determination of Serum Levels*

Cited by 50 publications

References 17 publications

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

Isolation and partial characterization of six somatomedin-like peptides from human plasma Cohn fraction IV

Protein Utilization in Growth: Effect of Lysine Deficiency on Serum Growth Hormone, Somatomedins, Insulin, Total Thyroxine (T₄) and Triiodothyronine, Free T₄Index, and Total Corticosterone

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Nonsuppressible Insulin-Like Activity (NSILA). I. Development of New Sensitive Competitive Protein-Binding Assay for Determination of Serum Levels*

Cited by 50 publications

References 17 publications

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

Somatomedin (Insulin-Like Growth Factors)-Binding Proteins

Isolation and partial characterization of six somatomedin-like peptides from human plasma Cohn fraction IV

Protein Utilization in Growth: Effect of Lysine Deficiency on Serum Growth Hormone, Somatomedins, Insulin, Total Thyroxine (T4) and Triiodothyronine, Free T4Index, and Total Corticosterone

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Product

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Protein Utilization in Growth: Effect of Lysine Deficiency on Serum Growth Hormone, Somatomedins, Insulin, Total Thyroxine (T₄) and Triiodothyronine, Free T₄Index, and Total Corticosterone