bluuebunny/crossref_metadata_2025_split huggingface dataset:
A role for insulin-like growth factor-I in the regulation of human thyroid cell growth by thyrotrophin
Authors: Ollis C. A. , Hill D. J. , Munro D. S. 
Published: December 2008

ABSTRACT
Human thyroid epithelial cells in monolayer culture were found to release radioimmunoassayable insulinlike growth factor-I (IGF-I) over a 48-h culture period in serum-free medium. In the presence of supraphysiological concentrations of TSH (1–100 mU/ml) known to be inhibitory to DNA synthesis by human thyroid cells, the release of IGF-I was found to be inhibited in six thyroid cultures studied. In only one out of the six was IGF-I release increased in the presence of physiological mitogenic concentrations of TSH (0·1–100 μU/ml). Human thyroid fibroblasts, established by long-term culture of thyroid epithelial cells under fibroblast-selective conditions, also secreted IGF-I which was unaffected by the presence of TSH at both low and high concentrations.
Using a monoclonal antibody against human IGF-I, monolayer cultures of both human thyroid epithelial cells and human thyroid fibroblasts showed positive immunocytochemical staining for IGF peptide. However, fixed sections of intact thyroid tissue only showed positive staining for IGF peptide associated with the fibrous layers surrounding the thyroid follicle, with no staining of the follicular epithelial cells.
The growth of human thyroid epithelial cells was also found to be increased by IGF-I (25–100 ng/ml) added in medium plus 1 % fetal calf serum as assessed by the incorporation of [3H]thymidine into DNA. In the presence of a monoclonal antibody to IGF-I the increase in [3H]thymidine uptake in response to IGF-I was abolished as was that seen in response to TSH.
This study indicates a possible paracrine/autocrine role of IGF-I in the regulation of human thyroid epithelial cell proliferation by interaction with TSH.
Journal of Endocrinology (1989) 123, 495–500
AN ENZYME-LINKED IMMUNOSORBENT ASSAY FOR CORTISOL IN THE SALIVA OF MAN AND DOMESTIC FARM ANIMALS
Authors: Cooper T.R. , Trunkfield H.R. , Zanella A.J. , Booth W.D. 
Published: December 2008

ABSTRACT
An enzyme-linked immunosorbent assay has been developed for the direct assay of cortisol in the saliva of man, sheep, calf and pig. The assay is sensitive (∼1 pg), highly specific and reproducible, and has the advantage over radioimmunosassay in being cheaper and quicker to carry out. The relatively-non invasive method of collecting saliva on cotton buds coupled with simple assay equipment provide a good potential for assessing cortisol status in studies on stress and welfare in farm animals as well as the possibility of monitoring cortisol status in mammals generally.
Pattern of serum concentrations of prolactin and progesterone during pregnancy and lactation in the brown hare (Lepus europaeus)
Authors: Caillol M. , Mondain-Monval M. , McNeilly A. S. 
Published: December 2008

ABSTRACT
A heterologous radioimmunoassay system developed for the rabbit has been shown to measure prolactin in the hare. Concentrations of prolactin showed a significant (P<0·01) increase in the last 3 days of pregnancy (87·7±11·7 compared with 9·8 ± 1·4 (s.e.m.) μg/l; n= 10 and 9 respectively) in pregnant females isolated from males, as well as in pregnant females kept with males and mating prepartum. This rise of prolactin at the end of pregnancy was not due to mating stimuli and occurred at a time when progesterone levels were still high (159 nmol/l). The injection of a slow-release preparation of bromocriptine (5 mg s.c.), which reduces prolactin secretion at the end of pregnancy, did not impair parturition. During lactation, prolactin levels increased significantly (61·2±19·8 compared with 5·3 ± 0·1 μg/l; P<0·01) only after suckling stimuli.
Journal of Endocrinology (1990) 124, 11–17
Chemical and biological characterization of chicken insulin-like growth factor-II
Authors: Kallincos N. C. , Wallace J. C. , Francis G. L. , Ballard F. J. 
Published: December 2008

ABSTRACT
Chicken insulin-like growth factor-II (cIGF-II) has been characterized by amino acid sequencing, by its receptor and binding protein interactions and by its biological activities in cultured cells in order to help define the significance of the peptide in the growth process. Chicken IGF-II has an N-terminal region and several amino acid substitutions in the mid-peptide region that differ from the mammalian growth factor. Nevertheless, cIGF-II was indistinguishable from ovine IGF-II in all assay systems, including those involving chicken receptors and chicken binding proteins. Thus the amino acid substitutions did not modify the biological activities. In chick embryo fibroblasts, labelled bovine IGF-II or cIGF-II bound to a receptor with size and specificity properties expected for a type 1 IGF receptor, except that IGF-I competition for binding was less than IGF-II competition. No evidence for a type 2 receptor was obtained. The relatively lower biological activity of IGF-I compared with IGF-II in chick embryo fibroblasts contrasts with the much higher potency of IGF-I in rat L6 myoblasts. This difference can be explained by a combination of an inhibitory, IGF-II-specific binding protein produced only by the rat cells as well as the unusual receptor specificity of the chicken cells.
Journal of Endocrinology (1990) 124, 89–97
3,5,3′-Tri-iodothyronine enhances sugar transport in rat thymocytes by increasing the intrinsic activity of the plasma membrane sugar transporter
Authors: Segal J. , Ingbar S. H. 
Published: December 2008

ABSTRACT
We have shown that 3,5,3′-tri-iodothyronine (T3) produces a prompt increase in sugar transport in rat thymocytes by increasing the maximal velocity without changing the Michaelis–Menten constant of the plasma membrane sugar transport system. To elucidate further the mechanism of this effect, we have now assessed the influence of T3 on the number and affinity of sugar transporters in thymocytes, measured as the sugar (2-deoxyglucose; dGlc)-displaceable binding of cytochalasin B. Cytochalasin B inhibited in a dose-related manner the uptake of dGlc by rat thymocytes with inhibition constant values of 0·19 and 0·22 μmol/l in the presence and absence of T3 respectively. Binding of cytochalasin B by the sugar-displaceable sites was rapid and saturable, demonstrating a single class of sites having an apparent dissociation constant of 0·33 ± 0·02 (s.d.) μmol/l and maximal binding capacity of 3·73±0·48 pmol/20 × 106 cells (11·2±1·4 × 104 sites/thymocyte). In the rat thymocyte, sugar transporters were found to be located in two major subcellular pools, the plasma membrane and microsomes, the latter being about twice the size of the former. In these subcellular compartments, as well as in the intact cell, binding of [3H]cytochalasin B by the sugar-displaceable sites constituted about 40% of total cytochalasin B binding.
3,5,3′-Tri-iodothyronine in concentrations that stimulated uptake of dGlc by thymocytes had no effect on [3H]cytochalasin B binding (total and sugar-displaceable) in the intact cell and in the plasma membrane and microsomal compartments, nor did it influence the affinity and number of sugar transporters. From these observations we conclude that, in the rat thymocyte, T3 acts to increase sugar uptake by increasing the intrinsic activity, i.e. the efficiency, rather than the number of sugar transporters.
Journal of Endocrinology (1990) 124, 133–140
Inhibitory effect of the uterus on plasma and pituitary FSH in rats
Authors: Biro J. C. , Eneroth P. 
Published: December 2008

ABSTRACT
Plasma concentrations of FSH and LH were measured in ovariectomized, ovohysterectomized, hysterectomized and sham-operated adult, non-pregnant rats at 3, 14, 21 and 28 days after operation. From day 21 after the operation onwards, there were higher concentrations of FSH in plasma in ovohysterectomized than in ovariectomized animals. The concentration of LH was not influenced by hysterectomy. The inhibitory response of FSH and LH to a single dose of oestradiol was not altered by any of the operations. By 2 weeks after surgery, pituitary FSH content had increased in ovohysterectomized animals compared with ovariectomized ones, but this difference was eliminated when ovohysterectomized animals were treated with crude uterine extract. Pituitary contents of LH and prolactin were not influenced by hysterectomy or by treatment with uterine extract, thus indicating the specificity of an inhibitory effect of the uterus on FSH levels. Treatment of hysterectomized and intact animals with uterine extract resulted in a reduction in the weight of the ovaries of 23–38% (P<0·05), indirectly showing the presence of an FSH-inhibiting substance in the extract.
Fractionated uterine extract inhibited FSH synthesis by rat pituitary cells in vitro, but had no effect on LH synthesis. Chromatographic analysis indicated that the FSH-inhibiting substance in the uterus has a molecular weight of 10 000–20 000.
Journal of Endocrinology (1990) 124, 183–189
The plasma pattern of growth hormone in conscious rats during late pregnancy
Authors: Carlsson L. , Edén S. , Jansson J.-O. 
Published: December 2008

ABSTRACT
The plasma GH levels of female rats during late pregnancy were determined using an automatic method for repetitive blood sampling from conscious animals. The plasma GH patterns were analysed by a pulse analysis computer program (PULSAR). The mean plasma GH levels were about twofold higher in pregnant females on days 15, 18 and 22 of gestation than in age-matched non-pregnant females. The basal plasma GH levels were also increased, while there was no change in GH pulse amplitude or frequency. The augmentation of GH release was even more pronounced on day 20 of gestation, with a fourfold increase in mean plasma GH levels compared with those in non-pregnant females. This increase reflected an increase in both basal plasma GH levels and GH pulse amplitude, but there was no increase in pulse frequency. In female rats that delivered on day 22 of gestation, the basal and mean plasma GH levels increased during parturition.
Pregnant females consistently responded to multiple i.v. infusions of 1 μg human GH-releasing factor analogue (hGRF(1–29)-NH2) given at 45-min intervals on day 18 of gestation. Both basal and GRF analogue-stimulated plasma GH levels were undetectable after hypophysectomy of pregnant rats.
The present study demonstrates an increase in basal plasma GH levels during late pregnancy and a marked increase in both basal plasma GH levels and GH pulse amplitude on day 20 of gestation. Furthermore, hypophysectomy of pregnant rats results in undetectable GH levels, indicating that the high levels of GH during pregnancy are derived from the pituitary.
Journal of Endocrinology (1990) 124, 191–198
Growth hormone (GH) autofeedback action in the neonatal rat: involvement of GH-releasing hormone and somatostatin
Authors: Cella S. G. , De Gennaro Colonna V. , Locatelli V. , Moiraghi V. , Loche S. , Wehrenberg W. B. , Müller E. E. 
Published: December 2008

ABSTRACT
It is known that in adult rats, GH by itself and by promoting secretion of the somatomedins acts at the level of the hypothalamus to trigger release of somatostatin and decrease output of GH-releasing hormone (GHRH), thereby inhibiting further secretion of GH. To assess whether these mechanisms are already operative in the early postnatal period, we have evaluated the effect of short-term administration of GH in 10-day-old rats. Twice-daily s.c. administration of 25 μg human GH/rat, from days 5 to 9 of life, significantly reduced pituitary content of GH, decreased hypothalamic levels of GHRH mRNA and abolished the in-vivo GH response to a challenge dose of GHRH (20 ng/100 g body weight, s.c.). GHRH (20 ng/100 g body weight, twice daily, s.c.) given concomitantly with the GH treatment, completely counteracted the inhibitory effect of the latter on pituitary content of GH and restored to normal the in-vivo GH response to the GHRH challenge. These data indicate that impaired secretion of GHRH is involved in the inhibitory effect elicited by GH treatment in infant rats. However, concomitant involvement of hypothalamic somatostatin as a result of GH treatment cannot be ruled out. In fact, pituitaries from rats pretreated with GH responded in the same manner as pituitaries from control rats to the GHRH challenge in vitro.
Journal of Endocrinology (1990) 124, 199–205
Regulation of oxytocin secretion by the ovine corpus luteum: effect of activators of protein kinase C
Authors: Hirst J. J. , Rice G. E. , Jenkin G. , Thorburn G. D. 
Published: December 2008

ABSTRACT
The effect of protein kinase C activation and dibutyryl cyclic AMP on oxytocin secretion by ovine luteal tissue slices was investigated. Several putative regulators of luteal oxytocin secretion were also examined. Oxytocin was secreted by luteal tissue slices at a basal rate of 234·4 ± 32·8 pmol/g per h (n = 24) during 60-min incubations.Activators of protein kinase C: phorbol 12,13-dibutyrate (n = 8), phorbol 12-myristate,13-acetate (n = 4) and 1,2-didecanoylglycerol (n = 5), caused a dose-dependent stimulation of oxytocin secretion in the presence of a calcium ionophore (A23187; 0·2 μmol/l). Phospholipase C (PLC; 50–250 units/l) also caused a dose-dependent stimulation of oxytocin secretion by luteal slices. Phospholipase C-stimulated oxytocin secretion was potentiated by the addition of an inhibitor of diacylglycerol kinase (R59 022; n = 4).
These data suggest that the activation of protein kinase C has a role in the stimulation of luteal oxytocin secretion. The results are also consistent with the involvement of protein kinase C in PLC-stimulated oxytocin secretion. The cyclic AMP second messenger system does not appear to be involved in the control of oxytocin secretion by the corpus luteum.
Journal of Endocrinology (1990) 124, 225–232
Pharmacological effects of the continuous administration of an LHRH agonist in the ageing male rat: comparison with orchidectomy
Authors: Amir-Zaltsman Y. , Ausher Y. , Gayer B. , Lichter S. , Serour F. , Birkenfeld S. , Kohen F. 
Published: December 2008

ABSTRACT
The age-related changes in tissue response to chronic treatment for 1 month with a potent LHRH agonist were investigated in the ageing male rat, and the observed pharmacological effects were compared with orchidectomy. In both young (4 months) and old (22 months) rats, treatment resulted in a significant decrease in the weights of prostates and testes, a decrease in plasma LH and testosterone levels, a loss of LH receptors in the testes and in a complete depletion of prostatic nuclear androgen receptors, reaching levels observed after castration. In young rats, treatment with an LHRH agonist or orchidectomy induced a three- or sixfold increase in prostatic creatine kinase (CK) activity which may have been induced by the local stimulatory effect of oestradiol arising from the conversion of precursor steroids secreted by the adrenal. On the other hand, in old rats, 7 days after orchidectomy or after treatment with an LHRH agonist a twofold increase or no change was induced in prostatic CK activity respectively. SDS gel electrophoresis patterns of cytosolic prostatic proteins of young rats treated with an LHRH agonist or young rats orchidectomized 7 days previously revealed the presence of several intensified proteins, two of them having apparent molecular weight of 67 kDa and 43 kDa, whereas in the old rats treated with LHRH agonist or old rats castrated 7 days previously, these two proteins were not intensified. The results of this study confirmed that continuous treatment with an LHRH agonist to young and old rats induces medical castration since the pharmacological effects observed were the same as those induced with surgical castration. However, in the old rats, the lack of an increase in prostatic CK activity upon treatment with LHRH agonist, and the moderate increase in CK activity upon orchidectomy, suggest that prostatic cells in older rats have decreased sensitivity to hormonal manipulation.
Journal of Endocrinology (1990) 124, 261–268
Characterization of growth factor activity produced by fetal mouse osteoblasts
Authors: Slootweg M. C. , van Buul-Offers S. C. , Hoogerbrugge C. M. , Herrmann-Erlee M. P. M. , van den Eijnden-van Raaij A. J. M. , Duursma S. A. , van Zoelen E. J. J. 
Published: December 2008

ABSTRACT
Bone matrix contains a variety of growth factors, but little is known of osteoblastic production of such materials. The present study assesses growth factor activity, chromatographed on acidic Bio-Gel P-100, secreted into conditioned media of primary cultures of fetal mouse calvaria. The cultures produced insulin-like growth factor-I (IGF-I), determined by radioimmuno-assay of molecular weights 20 and 10 kDa. IGF-II, determined by radioreceptor assay, was present at 20–29 and 7 kDa. The IGF peaks at 20, 10 and 7 kDa were all mitogenic in MCF-7 cells. Proteins of several different molecular weights were also present that specifically bound IGF-I and IGF-II. Transforming growth factor-β (TGF-β), assayed in a system for inhibition of growth, was also produced. Both activated and latent forms were present, and part of the TGF-β was TGF-β2. The absence of mitogenic activity in the bmolecular range of platelet-derived growth factor, assayed in 3T3 fibroblasts, makes it unlikely that mouse osteoblasts produce this growth factor.
Journal of Endocrinology (1990) 124, 301–309
Plasma clearance of chicken and human insulin-like growth factor-I and their association with circulating binding proteins in chickens
Authors: Francis G. L. , McMurtry J. P. , Johnson R. J. , Ballard F. J. 
Published: December 2008

ABSTRACT
We have investigated the clearance of 125I-labelled chicken and recombinant human insulin-like growth factor-I (IGF-I) from the circulation of chickens as well as the role that IGF-binding proteins play in this process. Analysis of plasma samples by high-performance liquid chromatography (HPLC) neutral gel permeation on a TSK G3000SW column indicated that the i.v. injected radioactivity was rapidly partitioned between at least three pools. Most of the radioactivity occurred in a complex with binding protein(s), while smaller amounts of radioactivity chromatographed in the free IGF-I peak or appeared as low molecular weight degradation products. The labelled chicken and human IGF-I were rapidly cleared during the first 90 min. The calculated half-life for total labelled IGF-I during this period was 54 min for the chicken tracer and 33 min for the human tracer. The clearance was monitored for 10 h during which the human tracer continued to be cleared more rapidly than the chicken tracer. The proportion of radioactivity appearing as low molecular weight degradation products increased with time. Acid gel permeation and reverse-phase HPLC of the binding protein-associated radioactivity demonstrated that the labelled IGF-I bound was intact IGF-I. Sephadex G-200 gel permeation chromatography of chicken plasma samples at pH 7·4 showed that the binding protein complex labelled in vivo with chicken IGF-I tracer had a molecular mass of 55 kDa. Furthermore, the tracer associated with the binding protein coeluted with the major peak of endogenous IGF-I, suggesting that the tracer was bound to the physiologically relevant binding protein. Similar results were obtained with Superose 12 chromatography. Human plasma chromatographed as expected with much of the immunoreactivity and the labelled IGF-I eluting with a mass of 150 kDa on both Sephadex G-200 and Superose 12 columns. Ligand blotting of plasma binding proteins with 125I-labelled IGF-I after first subjecting the samples to polyacrylamide gel electrophoresis and transfer to nitrocellulose confirmed that the predominant binding protein in chicken plasma differed from the major forms in human plasma.
Journal of Endocrinology (1990) 124, 361–370
Effects of passive immunization of growing guinea-pigs with an insulin-like growth factor-I monoclonal antibody
Authors: Kerr D. E. , Laarveld B. , Manns J. G. 
Published: December 2008

ABSTRACT
The physiological importance of circulating as opposed to locally produced insulin-like growth factor-I (IGF-I) has not been determined. By using a passive immunoneutralization technique, our objectives were to evaluate the role of circulating IGF-I in the regulation of animal growth and pituitary GH content.
A monoclonal antibody (MAb) to IGF-I, generated in our laboratory, has an affinity (Ka) of 0·13 litres/pmol for recombinant human IGF-I (rhIGF-I). Cross-reactivities of recombinant des-tripeptide IGF-I and recombinant bovine IGF-II were approximately 40 and 8% respectively. This MAb inhibited binding of purified hIGF-I to human placental membranes. In a radioimmunoassay based on displacement of 125I-labelled rhIGF-I from the MAb, displacement curves generated with dilutions of acid–gel chromatography extracts of guinea-pig serum and rhIGF-I standards were parallel.
Twenty-four, 3-week-old male guinea-pigs were treated with the IGF-I MAb, a bovine herpes virus-I (BHV-I) MAb (control MAb) or vehicle (phosphate-buffered saline) (n = 8 per group). Treatments were administered i.p. every 3 days for 24 days at a dose of 20 mg/kg body weight. Blood was obtained on day 23 (48 h after treatment) and on day 25 (24 h after treatment). In a liquid-phase assay, serum from the IGF-I MAb-treated group bound 38 ± 8% (mean ± s.e.m.) (day 23) and 56 ± 7% (day 25) of an 125I-labelled rhIGF-I trace at a final dilution of 1:10 000. Because of the development of an anti-mouse immune response in the guinea-pigs, these parameters would probably have been much greater during the first 2 weeks of the trial. Of the total IGF-I in serum, 50 ± 5% and 61±4% could be immunoprecipitated with an excess of rabbit anti-mouse immunoglobulin in samples from days 23 and 25 respectively. Comparisons between the groups treated with IGF-I MAb and BHV-I MAb revealed no significant differences in whole animal growth rate, growth of individual tissues, or pituitary GH content. Mean serum concentrations of IGF-I were 69 and 99% greater in IGF-I MAb-treated group than in the BHV-I MAb-treated group on days 23 and 25 respectively. These differences probably resulted from an extension of the half-life of IGF-I in serum of animals treated with the IGF-I MAb.
The lack of effect of treatment with the IGF-I MAb suggests that local production of IGF-I is generally sufficient to maintain normal growth or that local production or activity of IGF-I is increased in a compensatory fashion.
Journal of Endocrinology (1990) 124, 403–415