Recognition of growth hormone secretory disorders.
Explore the source record for details and available documents.
Body Height↗
Biomedical subjects
W H Daughaday
Publications and source records attributed to W H Daughaday.
Cushing's disease and basophilic microadenomas.
Explore the source record for details and available documents.
Adenoma↗
Insulin-like growth factor II receptors. Molecular radius and molecular weight determination using quantitative polyacrylamide gel electrophoresis.
High resolution quantitative polyacrylamide gel electrophoresis was employed under nondenaturing conditions to calculate a molecular weight, Mr, for rat placental membrane receptors that bind insulin-like growth factor II (IGF-II). An n-octylglucoside-soluble extract of receptors that had been enriched 20-fold during Sephacryl S-300 gel chromatography and designated peak 1 (Perdue, J. F., Chan, J. K., Thibault, C., Radaj, P., Mills, B., and Daughaday, W. H. (1983) J. Biol. Chem. 258, 7800-7811) was incubated with 125I-IGF-II in the presence or absence of an excess of unlabeled IGF-II and electrophoresed in glass tubes containing highly cross-linked polyacrylamide gels at concentrations ranging from 5 to 12% (w/v). A specifically labeled peak of IGF-II binding activity was identified by freezing, slicing, and counting the gels. The proteins eluted from the region of the gel when cross-linked to 125I-IGF-II with disuccinimidyl suberate and electrophoresed in the presence of sodium dodecyl sulfate have the same molecular weight, Mr, as the previously described IGF-II receptor. From the slope of a plot of log of the relative mobility, RF, at each of 6 to 7 gel concentrations for the 125I-IGF-II-receptor and for each of seven standard proteins (Ferguson-Hedrick plot), a retardation coefficient, KR, was determined. Using a reference curve constructed from a plot of square root KR versus the molecular radius, R, of the standard proteins, the IGF-II receptor was estimated to have a R of 4.13 nm and a calculated Mr of 250,000. Thus, quantitative procedures that separate native proteins based on their size and charge have provided information which is in good agreement with the results of studies of the IGF-II-receptor by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and supports the premise that it is a monomeric single chained glycoprotein, constrained by intradisulfide bonds and with a mass of 250 kDa.
Animals↗
Physiological and possible clinical significance of epidermal and nerve growth factors.
Explore the source record for details and available documents.
Amino Acid Sequence↗
Release of insulin-like growth factors and binding protein activity into serum-free medium of cultured human fibroblasts.
We have studied insulin-like growth factors (IGFs) and IGF-binding proteins released by human fibroblasts. Conditioned medium was obtained after incubation of 2 X 10(6) cells in 2 ml serum-free medium for 72 h. IGF binding protein was identified in aliquots of conditioned medium at 4 C for 16 h with [125]IGF II after charcoal separation. After gel filtration in neutral phosphate buffer through Sephadex G-150, the binding activity eluted with an apparent size greater than 100,000 daltons. After gel filtration through Bio-Rad P-100 in 1 M acetic acid, binding activity had a molecular size of about 50,000 daltons. When [125I]IGF-II bound to conditioned medium binding protein was cross-linked with disuccimidyl suberate and subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, the complex had an estimated molecular size of 67,000 daltons. Competitive binding studies with labeled and unlabeled IGF-I and IGF-II showed that IGF-II was preferentially bound by fibroblast binding protein. The above findings are characteristic of serum binding protein but not shed IGF surface receptors. To eliminate possible interference from binding proteins in the IGF-I RIA and the IGF-II radioreceptor assay, conditioned medium was subjected to acid gel filtration, and the peptide fractions were pooled. We found that conditioned medium of seven fibroblast lines contained 0.20 +/- 0.06 ng/ml IGF-I. After the addition of 20 ng/ml human GH (hGH), the conditioned medium contained 0.48 +/- 0.09 ng/ml. These results are lower than those previously reported. One of the two lines of fibroblasts from patients apparently resistant to GH had a minimal increase in IGF-I in conditioned medium after hGH addition. We were able to detect IGF-II in fibroblast conditioned medium in concentrations of 4.4 to 21 ng/ml but there was no consistent response to GH either in the normal fibroblast lines or in fibroblasts obtained from children with short stature.
Carrier Proteins↗
Comparison of growth and somatomedin C responses following growth hormone treatment in children with small-for-date short stature, significant idiopathic short stature and hypopituitarism.
Somatomedin-C (Sm-C) and growth hormone (GH) levels were determined before, during and after human growth hormone (hGH) treatment in 18 children with small-for-date short stature ( SDSS ), 7 children with significant idiopathic short stature ( SISS ) and 14 children with hypopituitarism. Data on the acute effects of hGH on Sm-C were compared to growth responses after 6 to 9 months therapy. Eleven of the 25 non-hypopituitary patients with normal basal and stimulated serum GH levels and normal basal Sm-C levels increased their rates of growth more than 3.0 cm/year. This compared with 11 of the 14 children with hypopituitarism who increased their rates of growth by at least 3.0 cm/year when treated with GH. Neither the basal somatomedin levels nor the GH-stimulated somatomedin levels correlated well with subsequent growth in the non-hypopituitary patients. These studies indicate that GH therapy may be effective in treating short stature in children without demonstrable GH deficiency.
Adolescent↗
The biochemical characterization of detergent-solubilized insulin-like growth factor II receptors from rat placenta.
A membrane preparation, the R3, obtained by differential centrifugation of rat placental homogenates is enriched in receptors that bind insulin-like growth factor II (IGF-II) preferentially and with avidity (Daughaday, W.H., Mariz, I.K., and Trivedi, B. (1981) J. Clin. Endocrinol. Metab. 53, 282-288). When this preparation was incubated with 2% (w/v) octyl-beta-D-glucopyranoside for 60 min at 0-4 degrees C, 60% of the membrane protein was solubilized without loss of binding activity. The 125I-IGF-II binding properties of the detergent-solubilized receptors were found to be similar to those of the membrane-associated receptor. The rate constants for association, ka, and dissociation, kd, and equilibrium dissociation constant, KD, were 8.5 X 10(8) M-1 min-1, 7.5 X 10(-3) min-1, and 1.3 nM for the detergent-solubilized receptors and 5.3 X 10(8) M-1 min-1, 4.2 X 10(-3) min-1, and 0.6 nM for the membrane receptors. Gel chromatography on Sephacryl S-300 concentrated the solubilized receptors into a major peak of binding activity with a Stokes radius of 7.2 nm; a second peak of less specific binding had a Stokes radius of 4.3 nm. The receptors in the major peak bound 125I-IGF-II with a KD of 0.6 nM; the total binding capacity, Ro, was 21.6 pmol mg of protein-1 compared to 1.6 pmol mg of protein-1 for the membrane-associated receptor. Centrifugation of the receptors on 5-20% (w/v) gradients of sucrose in H2O or D2O disclosed a heterogeneous pattern of receptor distribution. When they were labeled with 125I-IGF-II prior to centrifugation, a major form of the receptor with a sedimentation constant, S20,w, of 9.9 X 10(13) s and other, possibly smaller, forms of the receptor were observed. However, only the 9.9 s20,w form of the receptor was observed if it was labeled with 125I-IGF-II subsequent to centrifugation. Based on these hydrodynamic measurements and a partial specific volume of 0.72 cm3/g, the IGF-II receptor was calculated to have a Mr of 290,000 and frictional ratio, f/fo, of 1.6. This value for the Mr is similar to the mass of 220,000 or 250,000 Dal determined by cross-linking 125I-IGF-II to the membrane- or detergent-solubilized receptors with disuccimidyl suberate and separating the complex by electrophoresis in sodium dodecyl sulfate-containing polyacrylamide gels in the absence or presence of dithiothreitol, respectively.
Animals↗
Fetal and maternal virilization associated with pregnancy. A case report and review of the literature.
A masculinized female infant was born to a mother who had virilizing signs dating from the fourth month of pregnancy. Serum 17 alpha-hydroxyprogesterone, dehydroepiandrosterone, and testosterone levels were all normal in the infant. Maternal testosterone level was markedly elevated one week post partum. Dexamethasone phosphate suppression was normal. Human chorionic gonadotropin stimulation five weeks post partum revealed further elevation of high baseline free and total testosterone levels. Free and total testosterone levels 30 weeks post partum were normal, and all maternal virilizing signs had regressed with the exception of her deepened voice. The child has had no progression of masculinization. The mother is believed to have had a luteoma of pregnancy.
Adult↗
Growth hormone--dependent growth failure.
Growth failure may be associated with low serum somatomedin concentrations despite normal to increased concentrations of serum growth hormone. We have recognized five patients who responded to GH administration with an increase in serum Sm and an acceleration in skeletal growth, and have characterized the circulating GH in an homologous human GH radioreceptor assay employing the IM-9 lymphocyte as a source of human GH receptor. These five prepubertal children, who had a mean height 7.8 SD below the mean for age, had a mean RIA-GH of 34.2 +/- 3.5 ng/ml in response to stimulation, a basal Sm activity by hypophysectomized rat cartilage bioassay of less than 0.3 IU/ml, and a mean peak Sm of 0.9 +/- 0.1 IU/ml in response to 48 hours of GH therapy. During a one-year trial of GH therapy, four of these children significantly increased their growth velocity as compared to their growth rate before GH therapy. These children had a mean RIA-GH/RRA-GH ratio of 2.f. The fifth patient had a low RIA-GH/RRA-GH ratio and had no increase in growth rate. These studies suggest that growth in certain growth retarded children may be dependent on exogenous GH, even though they are not GH deficient by standard criteria.
Body Height↗
Measurement of somatomedin-related peptides in fetal, neonatal, and maternal rat serum by insulin-like growth factor (IGF) I radioimmunoassay, IGF-II radioreceptor assay (RRA), and multiplication-stimulating activity RRA after acid-ethanol extraction.
Previous measurements of somatomedins (Sms) and insulin-like growth factors (IGFs) in maternal and fetal serum have yielded contradictory results. We have, therefore, measured maternal, fetal, and neonatal rat serum with two highly specific assays: 1) IGF-I/Sm-C RiA and 2) a highly specific IGF-II/rat placental membrane radioreceptor assay (RRA). In addition, we have made measurements with a less specific multiplication-stimulating activity (MSA)-rat placental membrane RRA. To avoid possible serious artifacts created by Sm-binding proteins, preliminary acid-ethanol extraction of serum was performed. Results are expressed in terms of a reference human serum with an assigned potency of 1 U/ml. Maternal RIA IGF-I fluctuated between 1.1-1.4 U/ml from the 17th day of pregnancy to the 25th day after delivery (nonpregnant rat serum pool, 1.25 +/- 0.22 U/ml). On day 21 of gestation, fetal serum radioimmunoassayable IGF-I was 1.03 +/- 0.03 U/ml. After birth, radioimmunoassayable IGF-I fell and reached .19 +/- 0.03 U/ml at 18 days of age, but rose to 0.71 +/- 0.04 U/ml at 25 days of age. At term, maternal radioreceptor assayable IGF-II was 2.18 +/- 0.27 U/ml (nonpregnant female pool, 1.4 +/- 0.12). By the 25th postpartum day, radioreceptor assayable IGF-II was 1.39 +/- 0.12 U/ml. Radioreceptor assayable IGF-II in fetal serum on day 19 was 3.26 +/- 0.48 U/ml and rose to 5.37 +/- 0.66 U/ml on the day of delivery. A further rise to 8.92 +/- 1.03 occurred on day 5. A subsequent fall to 2.41 +/- 0.05 U/ml was observed on day 25. The patterns of results of the MSA RRA in fetal and neonatal rat serum were similar to that obtained with the IGF-II RRA. We now conclude that radioimmunoassayable IGF-I is present in higher concentrations than previously reported in term fetal rat serum and that radioreceptor assayable IGF-II is selectively elevated in rat fetal and neonatal life and may have unique metabolic and growth-promoting significance.U
Animals↗
Isolation and partial sequence analysis of rat basic somatomedin.
Rat basic somatomedin (Sm) was prepared with an improved purification scheme from the pooled sera of Wistar Furth rats previously inoculated with cells from the pituitary tumor MStT/W15. Amicon hollow fiber diafiltration facilitated the processing of large batches of serum, eliminating the necessity of running smaller portions of material on gel filtration columns to achieve the same qualitative separation. The yield from this technique was excellent. Basic rat Sm was separated from a C3ades Arg component of complement by a narrow pH range isoelectric focusing step. Subsequent chromatography on carboxymethyl-cellulose and Sephadex resins was very efficient, providing a 100-fold purification, with a recovery of Sm activity of approximately 65%. The final product was judged to be pure by a variety of criteria. Structural analysis of this material has demonstrated that the amino-terminal sequences of rat basic Sm and human insulin-like growth factor I are strikingly similar, confirming the homology proposed earlier on the basis of receptor cross-reactivity.
Amino Acid Sequence↗
Kinetics of the somatomedin C/insulin-like growth factor I: response to exogenous growth hormone (GH) in GH-deficient children.
The somatomedin C/insulin-like growth factor I (SMC/IGF-I) response to human GH (hGH) therapy and the t1/2 of SMC/IGF-I after the cessation of hGH were determined in 15 children with GH deficiency. After 5 injections of hGH (0.1 U/kg), there was a significant increase in total SMC/IGF-I [from 0.27 +/- 0.06 to 1.19 +/- 0.17 U/ml (mean +/- SEM)]. Both the pretreatment SMC/IGF-I and the maximal SMC/IGF-I levels attained were correlated with chronological age and bone age. Body size, as indicated by height and weight, also correlated with pretreatment and maximal SMC/IGF-I levels. For both pretreatment and maximal SMC/IGF-I levels, there was a better correlation of SMC/IGF-I levels with bone age than with chronological age. While the correlation between height and the pretreatment SMC/IGF-I level was stronger, weight was a better predicter of the maximal SMC/IGF-I level. Maximal SMC/IGF-I levels were reached 18.8 +/- 2.9 h after the last hGH injection. The t1/2 for SMC-IGF-I after the attainment of maximal levels was 20.7 +/- 2.3 h, or 39.5 +/- 3.8 h from the last injection of hGH. The t1/2 of SMC/IGF-I determined in this way was longer than previous values reported from studies in the rat. The relatively long t1/2 of SMC/IGF-I which we observed may in part explain the success of present GH treatment regimens which involve every other day injections of hGH.
Adolescent↗
Homologous IM-9 lymphocyte radioreceptor and receptor modulation assays for human serum growth hormone.
Radioreceptor assays for human GH (hGH) have been developed using the IM-9 cultured human lymphoid cell receptor. Varying degrees of nonspecific interference with [125I] hGH binding to these cells occurs in the presence of serum. We have modified the traditional IM-9 competitive binding assay for hGH and abolished the nonspecific serum effects. The modified competitive assay is sensitive to as little as 2 ng/ml hGH, and it has been validated by the quantitative recovery of purified pituitary hGH in hypopituitary serum. Sera from stimulated normals, acromegalics, and patients with severe growth retardation were assayed. The RIA to radioreceptor assay ratios for these groups were 0.98 +/- 0.10, 0.97 +/- 0.18, and 2.43 +/- 0.54, respectively. The assay has potential usefulness in screening and predicting growth-retarded patients most likely to respond to exogenous hGH therapy. In addition, a sensitivity receptor modulation assay, which uses the ability of hGH to regulate its homologous IM-9 receptors, is described. This is 8- to 10-fold more sensitive than the nonregulatory assays and has been applied to the measurement of hGH in sera from unstimulated normals and acromegalics. The ratios of RIA to receptor modulation assay for the two groups were 1.17 +/-0.68 ad 1.07 +/- 0.26, respectively. These sensitive receptor assays offer a powerful technique for the measurement of biologically active and inactive GH peptide in serum, and may be particularly useful in the evaluation of statural growth disorders.
Acromegaly↗
Characterization of somatomedin binding in human serum by ultracentrifugation and gel filtration.
It is known that the somatomedins exist in human serum complexed to specific binding proteins. The existence of unbound somatomedins in serum has never unequivocally been demonstrated. We have characterized the distribution of insulin-like growth factor (IGF) I in different fractions after gel filtration of serum through Sephadex G-200 in neutral buffer. IGF-I was measured by RIA after acid extraction. Seventy-two percent of serum IGF-I was associated with large complexes with an estimated size of about 150,000 daltons and 25% was associated with smaller complexes of about 50,000 daltons. No unbound IGF-I was detected. Ultracentrifugation of 10 ml fresh serum was carried out at 106,000 X g for 17 h, after which the tube was aspirated in 1-ml fractions beginning at the top. IGF-I by RIA in fractions 2 and 3 sedimented with albumin; in fractions 4 to 7, the sedimentation pattern approached that of immunoglobulin G. This shift is consistent with the size distribution of IGF-I complexes demonstrated by gel filtration. The failure to find any significant increase in the concentration of IGF-I relative to albumin in the top 30% of the tube (fractions 1-3) after centrifugation argues against the presence of measurable free IGF-I in these fractions. The ability of upper fractions to bind added [125I]IGF-II proved to closely approximate the binding of the initial serum, indicating little sedimentation of the accessible binding protein. The relative binding of [125I]IGF-II by serum aliquots proved to be markedly concentration dependent. At concentrations above 5% serum, the incremental increase of binding as a function of serum concentration was much reduced. We interpret this to indicate that with dilution there is a dissociation of complexes and an increase in accessible binding sites. This phenomenon may modify tissue delivery of somatomedins in interstitial fluid. The data suggest that in undiluted serum there is no significant concentration of free somatomedins but at the dilution of serum that exists in the interstitial fluid, dissociation of bound somatomedins may be facilitated.
Adult↗
Uremia reduces serum insulin-like growth factor I, increases insulin-like growth factor II, and modifies their serum protein binding.
Explore the source record for details and available documents.
Adult↗
Free myo-inositol in canine kidneys: selective concentration in the renal medulla.
Explore the source record for details and available documents.
Animals↗
Divergence of binding sites, in vitro action, and secretory regulation of the somatomedin peptides, IGF-I and IGF-II.
Explore the source record for details and available documents.
Amino Acid Sequence↗
Sleep and growth hormone secretion in alcoholics.
The effect of alcoholism on slow wave sleep (SWS) and SWS-related human growth hormone (HGH) secretion was investigated in 8 sober male alcoholics and 13 non-alcoholic controls. Sleep onset was temporally correlated with both elevated HGH levels and a high percentage of SWS in control subjects, with several specific qualifications related to age. By contrast, alcoholism was associated with a dissociation of sleep onset, SWS, and HGH elevation. The first noticeable HGH elevation in sober alcoholics often occurred several hours after sleep onset and in the absence of any SWS in the same time interval. Acute intoxication appeared to "normalize" the sleep onset-SWS linkage in alcoholics but did not influence the dissociation of HGH elevation from sleep onset and SWS.
Adult↗