bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-term reductions in GH, insulin-like growth factor-I and body weight gain in rats treated neonatally with antibodies to rat GH
Authors: Gardner M. J. , Flint D. J. 
Published: December 2008

ABSTRACT
Treatment of neonatal rats on days 2–5 with antibodies against rat GH (rGH) markedly reduced body weight gain and serum concentrations of insulin-like growth factor-I for 6–8 weeks in both females and males, after which weight gain normalized without evidence of catch-up growth. There were no significant effects on serum prolactin, tri-iodothyronine or corticosterone. Testis and ovarian weights were reduced, although only in proportion to body size. In females, but not males, the treated rats, though lighter, had increased fat deposition in the parametrial depot. Pituitary weight was considerably reduced over 100 days later, as was the pituitary content of GH, but not prolactin. The response to GH-releasing factor of both male and female rats was also greatly reduced at this time. Taken together with the fact that these rGH antibodies can bind directly to somatotrophs, we propose that the long-term effects of the antibodies are induced by specific somatotroph destruction.
Journal of Endocrinology (1990) 124, 381–386
Starvation decreases insulin secretion, prostaglandin E2 production and phospholipase A2 activity in rat pancreatic islets
Authors: Tadayyon M. , Bonney R. C. , Green I. C. 
Published: December 2008

ABSTRACT
Pancreatic islets, isolated from rats starved for 48 h, secreted significantly less insulin in the presence of 2 mmol glucose/l than islets of fed controls. In contrast, the insulin secretory response of islets from fed and starved rats to a challenge of 20 mmol glucose/l was similar. Concentrations of prostaglandin E2 (PGE2) in islets from starved rats incubated with 2 mmol glucose/l were significantly lower compared with those in control islets obtained from fed animals. Although glucose (20 mmol/l) stimulated PGE2 production in islets from starved and fed rats by 2·7- and 1·6-fold respectively, the concentrations achieved were the same as a consequence of the different prestimulated concentrations. Incubation with [14C]arachidonic acid of sonicated islet preparations from fed rats and separation of metabolites generated by high-pressure liquid chromatography, indicated the biosynthesis of a number of cyclo-oxygenase- and lipoxygenase-derived compounds, including 6-keto-PGF1α, PGF2α, PGE2 and 12-hydroxyeicosatetraenoic acid. Metabolism of arachidonic acid to cyclo-oxygenase-derived compounds occurred with the same efficiency, but production of lipoxygenase-derived compounds was reduced by 50% in sonicated islets from starved compared with fed rats. Activity of phospholipase A2 of islets from starved rats was significantly less than that measured in islets from fed rats, although the degree of stimulation by 20 mmol glucose/l was the same in both types of islet. These alterations in the phospholipase A2/arachidonic acid cascade may contribute to the diminished insulin secretory response of islets from starved rats to relatively low concentrations of glucose.
Journal of Endocrinology (1990) 124, 455–461
Bovine atrial natriuretic peptide in heart failure
Authors: Takemura N. , Koyama H. , Sako T. , Ando K. , Motoyoshi S. , Marumo F. 
Published: December 2008

ABSTRACT
The present study describes the concentration and molecular form of atrial natriuretic peptide (ANP) in Holstein dairy cattle with mild (bacterial endocarditis; BEC) or severe (dilated cardiomyopathy; DCM) heart failure. Significant increases in plasma concentration of ANP were observed in cattle with DCM (73·3 ± 16·02 pmol/l, n=4, P<0·01) and BEC (20·6± 3·45 pmol/l, n=7, P<0·05), when compared with those in control cattle (14·5± 1·84 pmol/l, n= 12). The concentration of ANP in cattle with DCM was significantly (P<0·01) higher compared with that in cattle with BEC. Plasma concentration of ANP correlated significantly with right atrial pressure (r =0·95, P<0·01) and left ventricular end-diastolic pressure (r= 0·84, P<0·01). Gel-permeation chromatography of ANP in plasma and the right atrium from control and cattle with BEC revealed a single peak corresponding to the elution position of authentic human ANP(99–126) in plasma, and two peaks corresponding to those of authentic human ANP(99–126) and pro-ANP in the atrial extract. In cattle with DCM, however, peaks corresponding to the elution positions of authentic human β-ANP and/or pro-ANP were detected in addition to the peak corresponding to ANP(99–126). The content of ANP in the right atrium of cattle with DCM was significantly (P<0·05) increased compared with that in control cattle and those with BEC. The present study therefore suggests that the synthesis and secretion of ANP might be stimulated by atrial distention induced by increased atrial pressure. This suggestion is supported by the fact that the middle molecular weight form of ANP, possibly corresponding to human β-ANP, was detected in both the plasma and atria of the cattle with severe heart failure.
Journal of Endocrinology (1990) 124, 463–467
Gonadotrophin-binding components in porcine follicular fluid
Authors: Yarney T. A. , Sairam M. R. , Bhargavi G. N. , Downey B. R. , Srikandakumar A. 
Published: December 2008

ABSTRACT
The follicular fluid is an important milieu for the growing and maturing oocyte and granulosa cells. In this study we investigated: (1) the properties of gonadotrophin-binding sites in the supernatant fraction of porcine follicular fluid (pFF) and compared them with those of membrane-bound receptors, and (2) the relative changes that occur in pFF and granulosa cell receptor-binding activity following hormone priming of gilts. 125I-Labelled human chorionic gonadotrophin (hCG) and 125I-labelled ovine FSH (oFSH) binding to particulate and supernatant fractions of pFF were hormone-specific and saturable. The concentration of 125I-labelled hCG-binding sites was roughly 50-fold higher in particulate than in supernatant fractions of pFF. However, 30–40% of the total 125I-labelled hCG-binding activity in pFF was present in the supernatant fraction of commercial batches of pFF. 125I-Labelled oFSH binding to pFF membranes was markedly higher than to supernatant fractions. Binding of 125I-labelled hCG and 125I-labelled oFSH to granulosa cells and supernatants of pFF showed a time-dependent variation in response to hormone priming. The results suggest that gonadotrophin-binding sites in the supernatant fraction of pFF have properties similar to those of their membrane-bound counterparts. 125I-Labelled hCG-binding activity in the supernatant fraction of pFF was shown to be more stable than detergent-solubilized LH/hCG receptors, even in glycerol-preserved preparations. Based on a number of criteria, we have speculated that pFF may have components which may be similar in structure to the extracellular domain of the LH/hCG receptor.
Journal of Endocrinology (1990) 124, 485–494
Alterations of serum concentrations of thyroid hormones and sex hormone-binding globulin, nuclear binding of tri-iodothyronine and thyroid hormone-stimulated cellular uptake of oxygen and glucose in mononuclear blood cells from patients with non-thyroidal illness
Authors: Kvetny J. , Matzen L. 
Published: December 2008

ABSTRACT
Nuclear tri-iodothyronine (T3) binding and thyroid hormone-stimulated oxygen consumption and glucose uptake were examined in mononuclear blood cells from patients with non-thyroidal illness (NTI) in which serum T3 was significantly (P < 0·05) depressed (0·62± 0·12 (s.d.) nmol/l) compared with healthy control subjects (1·45 ± 0·30 nmol/l). Neither serum TSH nor sex hormone-binding globulin differed from that of the control group.
Nuclear T3 binding capacity was increased (P < 0·05) in patients with NTI (10·1 ± 3·0 fmol/100 μg DNA) compared with controls (2·5 ± 0-9 fmol/100 μg DNA). Unstimulated glucose uptake was increased in cells from patients with NTI (2·03 ± 0·49 mmol/l per mg DNA per h, P < 0·01) compared with controls (1·13 ± 0·20 mmol/l per mg DNA per h). Thyroxine-stimulated glucose uptake (stimulated glucose uptake–unstimulated glucose uptake) was increased in cells from patients with NTI (2·06 ± 1·67 mmol/l per mg DNA per h, P < 0·01) compared with controls (0·26 ± 0·1 mmol/l per mg DNA per h), and T3-stimulated glucose uptake was also increased in cells from patients with NTI (1·34 ± 0·81 mmol/l per mg DNA per h, P < 0·05) compared with controls (0·24 ± 0·10 mmol/l per mg DNA per h). In contrast, neither unstimulated nor thyroid hormone-stimulated oxygen consumption differed.
We conclude that both increased nuclear T3 binding and increased thyroid hormone-induced glucose uptake may represent counter-regulatory mechanisms which tend to maintain intracellular homeostasis.
Journal of Endocrinology (1990) 124, 495–499
EFFECT OF INSULIN-LIKE GROWTH FACTOR-TYPE I (IGF-I) AND INSULIN ON THE SECRETION OF SEX HORMONE BINDING GLOBULIN AND IGF-I BINDING PROTEIN (IBP-I) BY HUMAN HEPATOMA CELLS
Authors: Singh A. , Hamilton-Fairley D. , Koistinen R. , Seppälä M. , James V.H.T. , Franks S. , Reed M.J. 
Published: December 2008

ABSTRACT
Dietary factors are known to modulate concentrations of sex hormone-binding globulin (SHBG). In the present study we have investigated the possibility that insulin like growth factor-type I (IGF-I) may be an additional regulator of SHBG using cultured human hepatoma cells which secrete SHBG. The inhibitory effect of insulin on SHBG secretion by these cells was confirmed but, in addition, IGF-I was shown to inhibit SHBG secretion by about 40% at a concentration of 100 nmol/l. A similar degree of inhibition was achieved using insulin at a concentration of 10 umol/l. Insulin, but not IGF-I, was also found to inhibit the secretion of a low molecular weight IGF-binding protein (IBP-I), which is also secreted by hepatoma cells. It is concluded that IGF-I is an additional regulator of SHBG secretion by these cells and that it may be involved in regulating SHBG secretion in vivo in response to dietary factors.
OXYTOCIN BIOSYNTHESIS IN SERUM-FREE CULTURES OF HUMAN GRANULOSA CELLS
Authors: plevrakis I. , Clamagirand C. , Pontonnier G. 
Published: December 2008

ABSTRACT
Human granulosa cells were collected from preovulatory follicles during follicular puncture for in-vitro fertilization. They were cultured in serum-free medium supplemented with ascorbic acid. Using a combination of high-performance liquid chromatography and radioimmunoassay, the oxytocin material present in the cell extracts and secreted into the medium was identified. When cells were deprived of ascorbate, intermediary forms resulting of the post-translational processing of pro-oxytocin/neurophysin were detected. These data demonstrate that oxytocin biosynthesis occurs in human granulosa cells.
Comparison of the effects of crude and highly purified bovine inhibin (Mr 32 000) on plasma concentrations of FSH and LH in chronically ovariectomized prepubertal heifers
Authors: Beard A. J. , Castillo R. J. , McLeod B. J. , Glencross R. G. , Knight P. G. 
Published: December 2008

ABSTRACT
Chronically ovariectomized prepubertal heifers were used for a comparison of the effects of highly purified bovine inhibin (Mr 32 000) and steroid-free bovine follicular fluid (bFF) on the secretion of FSH and LH. In view of the limited availability of highly purified inhibin, an initial study was undertaken to establish the optimal method for administration of bFF inhibin activity. In comparison with the FSH response to a single large i.v. bolus injection of bFF (50 ml; 3250 mg protein), a far more effective suppression of plasma FSH concentrations was achieved when considerably less bFF (6·3 ml; 410 mg protein) was administered gradually over an extended time-period (2 days) either as a continuous i.v. infusion or as a series of 2-hourly i.v. injections. Following a single i.v. bolus injection of bFF, immunoreactive inhibin was cleared rapidly from the circulation (half-life 51 ± 8 (s.e.m.) min, n = 5), presumably accounting for its limited ability to suppress FSH secretion when administered in this manner.
In a second experiment, treatment of ovariectomized heifers (three per group) with highly purified Mr 32 000 bovine inhibin at a dose rate of 15 μg/2 h for 2 days significantly (P < 0·05) suppressed plasma FSH concentrations, which reached their minimum values (40% suppression) during day 2 of treatment. At a lower dose rate (5 μg/2 h), inhibin did not significantly affect plasma FSH levels. Administration of bFF was also associated with a dose-dependent suppression of FSH secretion. For each of three dose rates tested (three heifers per group), plasma FSH concentrations were maximally suppressed during day 2 of treatment (65 mg/2 h, 86% suppression, P < 0·001; 21·7 mg/2 h, 66% suppression, P < 0·001; 7·2 mg/2 h, 15% suppression, P > 0·05). Neither highly purified inhibin nor bFF significantly affected mean plasma LH concentrations, LH pulse frequency or LH pulse amplitude. Thus we have shown for the first time that highly purified Mr 32 000 bovine inhibin does possess in-vivo biological activity in cattle, promoting a selective suppression of plasma FSH concentrations qualitatively similar to that evoked by steroid-free bFF. Quantitatively, the inhibin preparation had an in-vivo biopotency about 1000 times greater than that of bFF, a value which accords well with its biopotency (1176 × bFF) in the in-vitro rat pituitary cell bioassay.
Journal of Endocrinology (1990) 125, 21–30
Enhancement of bovine growth hormone activity by antibodies against growth hormone peptides
Authors: Bomford R. , Aston R. 
Published: December 2008

ABSTRACT
The biological activity of growth hormones can be enhanced by complexing with monoclonal antibodies of appropriate specificity. In order to define the regions associated with the phenomenon, site-directed antisera to ovine GH (oGH) were prepared by vaccination of sheep with synthetic peptides. Peptides from six distinct regions of the oGH molecule raised antibodies which recognized the hormone in solid-phase radioimmunoassay; however, only one peptide elicited high-affinity antibody as determined by liquid-phase assay. This peptide, corresponding to amino acid sequence 35–53, resulted in circulating hormone antibody in the majority of vaccinated sheep. Immunoglobulin prepared from the serum of immunized animals produced an enhancement of the somatotrophic activity of exogenously administered GH in dwarf mice as determined by the incorporation of [35S]sulphate into costal cartilage. The identification of an antigenic peptide sequence from oGH/bovine GH which elicits enhancing antisera, raises the possibility of a growth-promotion vaccine.
Journal of Endocrinology (1990) 125, 31–38
Effect of cysteamine on the lysosomal enzymes of the hyperprolactinaemic rat pituitary
Authors: Jeitner T. M. , Oliver J. R. 
Published: December 2008

ABSTRACT
The effect of cysteamine on the activity of lysosomal enzymes and the prolactin content of isolated hyperprolactinaemic cells has been investigated. In broken cell preparations, cysteamine markedly stimulated acid prolactin protease activity. In intact cells, however, cysteamine inhibited acid prolactin protease activity and β-galactosidase. Moreover, the activities of α-mannosidase, acid phosphatase, β-glucuronidase, total arylsulphatase and hexosaminidase were not changed by the addition of cysteamine. Cysteamine significantly depleted the cells of prolactin, and this action was not compromized by the inclusion of either leupeptin, chloroquine or NH4Cl in the incubation media. Taken together, these results indicate that cysteamine does not promote degradation of prolactin and hence depletion of prolactin from the pituitary through a mechanism involving lysosomal enzyme degradation.
Journal of Endocrinology (1990) 125, 75–80
Effect of LH injections on testicular steroidogenesis, cholesterol side-chain cleavage P450 mRNA content and Leydig cell morphology in hypogonadal mice
Authors: Scott I. S. , Charlton H. M. , Cox B. S. , Grocock C. A. , Sheffield J. W. , O'Shaughnessy P. J. 
Published: December 2008

ABSTRACT
Hypogonadal (hpg) mice have a congenital deficiency of hypothalamic gonadotrophin-releasing hormone (GnRH) and the gonads consequently lack exposure to gonadotrophins during development. We injected male hpg mice with LH for 10 days to investigate whether LH alone can stimulate normal steroidogenesis in these animals. Control animals had an inactive interstitium and very few germ cells. Testicular content of androgens was undetectable by radioimmunoassay in control animals unless a single injection of LH was given 1 h before death, when androgens were just detectable. Control testes incubated in vitro with [3H]pregnenolone demonstrated that without gonadotrophin stimulation pregnenolone was metabolized only to progesterone in significant amounts. Assay for cholesterol side-chain cleavage cytochrome P450 (P450scc) mRNA showed basal expression in saline-treated hpg mouse testis. LH treatment induced hypertrophy and hyperplasia of Leydig cells and division of germ cells. Testicular androgen content increased significantly, with testosterone and androstenedione as the major androgens. LH-treated testes incubated with [3H]pregnenolone in vitro had a greater synthetic capacity for testosterone, suggesting an increase in 17α-hydroxylase/C17–20-lyase activity. Basal and human chorionic gonadotrophinstimulated androgen production in vitro increased markedly following LH treatment to levels previously described in the normal adult animal. LH treatment caused a rapid and transient increase in the hybridization of P450scc mRNA which was sevenfold greater than that of saline-treated controls when the animals were killed 1 h after the last injection but fell to control levels within 24 h of cessation of treatment.
We conclude that LH alone can stimulate steroidogenesis in testes of hpg mice, and that previous exposure of the tissue to physiological concentrations of endogenous gonadotrophins is not required to obtain normal steroidogenic responsiveness.
Journal of Endocrinology (1990) 125, 131–138
Circulating levels of GH-releasing hormone and GH during human pregnancy
Authors: Mazlan M. , Spence-Jones C. , Chard T. , Landon J. , McLean C. 
Published: December 2008

ABSTRACT
To study the potential role of GH-releasing hormone (GHRH) in maintaining circulating levels of GH during pregnancy, 302 maternal plasma samples were collected from non-fasted subjects at various stages of pregnancy and assayed for GHRH using a 'two-site' immunoradiometric assay. The GH and placental lactogen levels were also determined. In addition, maternal plasma samples taken during labour, amniotic fluid and cord blood were also assayed for these hormones.
Maternal plasma GHRH levels were similar to non-pregnant levels throughout gestation despite fluctuations in GH values which were always higher than non-pregnant levels. There was no significant difference between GHRH levels in maternal plasma and cord blood although high GH levels were observed in the latter. These findings suggest that peripheral GHRH levels do not play an important role in maintaining circulating GH levels during pregnancy.
Journal of Endocrinology (1990) 125, 161–167
Insulin-like growth factor receptors in chicken liver membranes: binding properties, specificity, developmental pattern and evidence for a single receptor type
Authors: Duclos M. J. , Goddard C. 
Published: December 2008

ABSTRACT
Two distinct receptors for the insulin-like growth factors (IGF-I and IGF-II) have been identified in mammalian tissues, but so far only a receptor structurally related to the type I receptor has been identified in chicken embryonic tissues. This study was designed to characterize binding sites for IGF peptides in chicken liver microsomal membranes prepared from hatch to 10 weeks of age which is the period of most rapid growth.
Binding of both human (h) IGF-I and hIGF-II was displaceable by either peptide and exhibited similar pH, time and temperature dependency. Human IGF-II was more potent than hIGF-I in competing for the binding of the iodinated ligands with half-maximum effective concentrations of 3–5 μg/l and 7–13 μg/l respectively. Porcine insulin was also a potent competitor. Affinity cross-linking studies, followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis under reducing conditions demonstrated that both IGF peptides were linked to a protein with a molecular weight of about 130 000 Da characteristic of the α-subunit of the type I receptor. There was no evidence for the presence of a type II receptor similar to that found in mammals.
Specific binding of both peptides was low on the day of hatch, increased about threefold by day 3 of age and remained high for the first 3 weeks of life before returning to a lower steady state level up to 10 weeks of age. This was the result of variation in receptor number, with no change in the affinity of the binding site for either ligand. The affinity constant for IGF-II (4·5 ± 0·5 (s.e.m.) litres/nmol) was higher than for IGF-I (1·4 ± 0·3 litres/nmol).
Insulin-like growth factors have previously been reported to stimulate the metabolism and growth of hepatocytes in vitro and are produced by these cells. The occurrence of a higher number of receptors at the period of most rapid growth of the liver suggests that they may have a role in regulating normal liver growth in an autocrine or paracrine manner. Furthermore, present evidence suggests that this is through a single receptor related to the type I receptor.
Journal of Endocrinology (1990) 125, 199–206
Purification and biological activity of a single charge isomer of pituitary-derived chicken growth hormone
Authors: Houston B. , O'Neill I. E. , Mitchell M. A. , Goddard C. 
Published: December 2008

ABSTRACT
The chicken pituitary gland contains a number of naturally occurring, developmentally regulated forms of GH which have identical molecular weights but differ in their isoelectric points. In order to characterize their biological properties, each must be separated from non-GH proteins and other forms of GH. Chicken GH (cGH) was separated from other pituitary proteins by immunoaffinity chromatography using an anti-GH monoclonal antibody covalently linked to Sepharose 4B. The cGH eluted from this column as a single peak and migrated as a single band during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), but showed multiple bands on isoelectric focussing. This material was chromatographed on a high-performance cation exchange column, and separation of charge isomers was monitored by a combination of isoelectric focussing and immunoblotting. Chicken GH eluted from this column in two distinct peaks. The minor peak (cGH P1) contained an isomer with an isoelectric point of 6·86 and the major peak (cGH P2) an isomer with an isoelectric point of 7·52. Each isomer migrated as a single band during isoelectric focussing and SDS-PAGE (Mr = 23 500), and as a single peak during high-performance gel permeation chromatography and reverse-phase high-performance liquid chromatography. Analysis of cGH P2 through 30 cycles in a gas-phase microsequencer gave an amino acid sequence identical to that predicted by translation of the GH complementary DNA nucleotide sequence.
This single charge isomer increased the rate of lipolysis in chicken adipose tissue explants by about fourfold and was able to displace 125I-labelled cGH from binding sites in liver membranes with a dissociation constant of about 4 nmol/l. The output of insulin-like growth factor-I by hepatocytes in culture was increased from a basal rate of 50·4±11·6 (mean ± s.e.m.) to 787·9 ± 98·6 pg/6 × 106 cells per 48 h by two separate pulses of 1 μg cGH P2/ml. An i.v. injection of cGH P2 (15 μg/kg body weight) decreased the thyroxine:tri-iodothyronine ratio in serum of adult hens from 15·71 to 4·44, indicating an increase in 5′-monodeiodinase activity. These results demonstrate that the single most abundant charge isomer of chicken pituitary GH is likely to contain all the biological activity ascribed to the hormone.
Journal of Endocrinology (1990) 125, 207–215