bluuebunny/crossref_metadata_2025_split huggingface dataset:
IGF-I and IGF-binding protein-3 in plasma of GH-deficient rats
Authors: Butler A A , Gallaher B W , Ambler G R , Gluckman P D , Breier B H 
Published: December 2004

Abstract
The majority of IGF-I circulates in a large (150 kDa) ternary complex with IGF-binding protein-3 (IGFBP-3) and a non-IGF-binding acid-labile subunit. The secretion of ternary complex into the circulation from liver has been considered to be GH-dependent; however, recent data indicate that GH does not directly regulate hepatic IGFBP-3 synthesis. To examine the role of insulin in regulating plasma IGFBP-3 levels, postpubertal male GH-deficient (dw/dw) rats were treated every 8 h with injections (s.c.) of 0·9% saline, 20 μg insulin/day, 200 μg hIGF-I/day, or 20 μg insulin/day plus 200 μg hIGF-I/day, for 10 days with the animals being killed 2–3 h after the final injection. Hypoglycaemia was not observed in any of the treatment groups. hIGF-I treatment increased longitudinal growth and weight gain (P<0·05), while insulin treatment had no effect. Plasma IGF-I levels were increased in groups treated with hIGF-I (P<0·05), while insulin treatment resulted in a reduction (P<0-05): saline=267·1 ± 15·6 (ng/ml ± s.e.m.), insulin=219·3 ± 17·5, hIGF-I=391·7 ± 17·6, insulin plus hIGF-I=357·5 ± 31·8. Hepatic IGF-I mRNA expression was increased in insulin-treated dw/dw rats in comparison with hIGF-I-treated animals (P<0·05) but not in comparison with saline control or the combined treatment groups. Plasma levels of intact IGFBP-3, measured by ligand blot analysis, were increased in all treatment groups compared with saline (P<0·05): saline=100·0 ± 9·4% (% of saline ± s.e.m.), insulin=149·9 ± 17·5%, hIGF-I= 191·4 ± 17·3%, insulin plus hIGF-I=205·4 ± 15·3%. The levels of the 28/32 kDa IGFBPs and IGFBP-4 in plasma were increased by hIGF-I treatment (P<0·05) but not by insulin treatment. Hepatic specific 125I-bovine GH binding was not significantly different in any of the treatment groups. This study provides the first evidence in non-diabetic animals that insulin regulates hepatic IGF-I mRNA expression, plasma IGF-I and plasma IGFBP-3 levels in the GH-deficient state without changes in hepatic GH receptors. The divergent response of plasma IGF-I and IGFBP-3 levels to insulin treatment in the present study may indicate an effect of insulin on the clearance of IGF-I from the circulation.
Journal of Endocrinology (1996) 150, 67–76
Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection
Authors: Tomas F M , Lemmey A B , Read L C , Ballard F J 
Published: December 2004

Abstract
The relative potency of IGF-I and the analogue LR3IGF-I to either promote growth or reverse catabolism in rats when administered by injection rather than by continuous infusion has been examined. LR3IGF-I has very low affinity for the IGF-binding proteins in the rat and hence is cleared from the circulation more quickly than is IGF-I. Experiments were performed in normal growing rats (150 g body weight) and in rats made catabolic by dexamethasone infusion (20 μg/day). IGFs or vehicle were delivered subcutaneously for 7 days either by continuous infusion via osmotic pumps or by injection once or twice daily at 320 and 400 μg/day in normal and catabolic rats respectively.
As expected, continuous infusion of IGFs showed greater efficacy than either of the injection modes especially in its anti-catabolic actions. When infused continuously LR3 IGF-I was generally 1·5- to 2-fold more potent than IGF-I for changes in body weight gain, visceral organ weights and feed use efficiency. Notably, LR3 IGF-I remained more potent than IGF-I in several of these effects even when the peptides were given by once-daily injection. In addition, Nτ-methylhistidine excretion by dexamethasone-treated rats was reduced to a threefold greater extent by injected LR3 IGF-I than by injected IGF-I. Notwithstanding these effects, LR3IGF-I was barely equipotent with IGF-I for reversal of carcass muscle loss in dexamethasone-treated rats.
Despite its more rapid clearance from the circulation, injected LR3IGF-I retains superior potency to injected IGF-I for several actions, albeit the potency is much reduced compared with continuous infusion. Thus our data indicate that use of IGF analogues which have low affinity for binding proteins may have advantages in potency and/or tissue specificity where IGFs are necessarily administered by injection.
Journal of Endocrinology (1996) 150, 77–84
Beta-cell markers and autoantigen expression by a human insulinoma cell line: similarities to native beta cells
Authors: Cavallo M G , Dotta F , Monetini L , Dionisi S , Previti M , Valente L , Toto A , Di Mario U , Pozzilli P 
Published: December 2004

Abstract
In the present study we have evaluated the expression of different beta-cell markers, islet molecules and autoantigens relevant in diabetes autoimmunity by a human insulinoma cell line (CM) in order to define its similarities with native beta cells and to discover whether it could be considered as a model for studies on immunological aspects of Type 1 diabetes.
First, the positivity of the CM cell line for known markers of neuroendocrine derivation was determined by means of immunocytochemical analysis using different anti-islet monoclonal antibodies including A2B5 and 3G5 reacting with islet gangliosides, and HISL19 binding to an islet glycoprotein. Secondly, the expression and characteristics of glutamic acid decarboxylase (GAD) and of GM2-1 ganglioside, both known to be islet autoantigens in diabetes autoimmunity and expressed by human native beta cells, were investigated in the CM cell line. The pattern of ganglioside expression in comparison to that of native beta cells was also evaluated. Thirdly, the binding of diabetic sera to CM cells reacting with islet cytoplasmic antigens (ICA) was studied by immunohistochemistry. The results of this study showed that beta cell markers identified by anti-islet monoclonal antibodies A2B5, 3G5 and HISL-19 are expressed by CM cells; similarly, islet molecules such as GAD and GM2-1 ganglioside are present and possess similar characteristics to those found in native beta cells; the pattern of expression of other gangliosides by CM cells is also identical to human pancreatic islets; beta cell autoantigen(s) reacting with antibodies present in islet cell antibodies (ICA) positive diabetic sera identified by ICA binding are also detectable in this insulinoma cell line.
We conclude that CM cells show close similarities to native beta cells with respect to the expression of neuroendocrine markers, relevant beta cell autoantigens in Type 1 diabetes (GAD, GM2-1, ICA antigen), and other gangliosides. Therefore, this insulinoma cell line may be considered as an ideal model for studies aimed at investigating autoimmune phenomena occurring in Type 1 diabetes.
Journal of Endocrinology (1996) 150, 113–120
Influence of insulin-like growth factor-binding protein-2 on plasma clearance and transfer of insulin-like growth factors-I and -II from plasma into mammary-derived lymph and milk of goats
Authors: Prosser C G , Schwander J 
Published: December 2004

Abstract
Plasma clearance of insulin-like growth factors-I and -II (IGF-I and -II) and insulin-like growth factor-binding protein-2 (IGFBP-2) from lactating goats (n=4) was determined following a single intravenous injection of the corresponding 125I-labelled human protein. Transfer of these proteins out of the vascular space was monitored by their subsequent appearance in mammary-derived lymph and milk. Clearance of 125I-IGFBP-2 from circulation was 0·37 ± 0·06 ml/min/kg, which is markedly greater than that of 125I-IGF-I or -II (0·11 ± and 0·12 ± 0·01 ml/min/kg respectively). This was also reflected in longer elimination half-lives for IGF-I (353 ± 6 min) and -II (254 ± 8 min) compared with IGFBP-2 (110 ± 9 min). Three hours after injection of the 125I-labelled protein, the plasma:lymph ratio of trichloroacetic acid-precipitable radioactivity was 1·54 ±0·04, 3·3 ±0·6 and 4·1 ±0·4 for IGFBP-2, IGF-I and -II respectively. The form of 125I-IGFBP-2 in lymph was not different from that of plasma. Elevation of plasma concentrations of IGFBP-2 by its intravenous infusion significantly decreased plasma half-life of both IGF-I and -II (251 ± 8 and 198 ±7 min respectively). Although the amount and rate of transfer of IGF into mammary-derived lymph was decreased slightly by IGFBP-2, concentrations eventually obtained were not different from control. However, secretion of IGFs into milk was significantly reduced by IGFBP-2, particularly in the case of IGF-I. These results are consistent with the ability of all three compounds to cross the vascular endothelium intact and of IGFBP-2 to decrease the uptake of IGF by mammary epithelium and subsequent secretion into milk. IGFBP-2 may well have acted to target plasma IGF towards non-mammary tissues, thus explaining the more rapid plasma clearance of IGFs in the presence of elevated IGFBP-2.
Journal of Endocrinology (1996) 150, 121–127
Cytochrome P450 17α-hydroxylase gene expression in differentiating rat trophoblast cells
Authors: Yamamoto T , Chapman B M , Johnson D C , Givens C R , Mellon S H , Soares M J 
Published: December 2004

Abstract
Trophoblast giant cells of the rat placenta express cytochrome P450 17α-hydroxylase (P450c17) and synthesize androgens. The purpose of this study was to investigate androgen production and expression of P450c17 in the Rcho-1 trophoblast cell line. These cells are capable of differentiating along the trophoblast giant cell lineage. Androstenedione production increased approximately 70-fold as Rcho-1 trophoblast cells progressed from the proliferation to the differentiation state. P450c17 enzyme activity and mRNA also showed significant increases associated with trophoblast giant cell differentiation. To study the transcriptional regulation of the P450c17 gene, the activities of a series of P450c17 promoter–luciferase reporter constructs were evaluated following transient transfection into Rcho-1 trophoblast cells. A DNA region located – 98 bp upstream of the P450c17 gene transcriptional start site was the shortest promoter DNA construct consistently possessing activity in Rcho-1 trophoblast cells. Activities of longer constructs (−156 to −1560 bp) in this population of cells were significantly greater than the −98 bp promoter–reporter construct. The − 476 bp P450c17 construct showed maximal promoter activity in transiently transfected Rcho-1 trophoblast cells and was developmentally activated in stably transfected Rcho-1 trophoblast cells. Activation of the cyclic AMP/protein kinase A pathway did not significantly affect P450c17 promoter activity in Rcho-1 trophoblast cells, in contrast to its effects in mouse MA-10 Leydig cells. In summary, Rcho-1 trophoblast cells are capable of endocrine differentiation and are a useful in vitro system for studying the regulation of trophoblast androgen production and P450c17 gene expression.
Journal of Endocrinology (1996) 150, 161–168
Effects of long-term food reduction on the hypothalamus-pituitary-thyroid axis in male and female rats
Authors: van Haasteren G A C , Linkels E , van Toor H , Klootwijk W , Kaptein E , de Jong F H , Reymond M J , Visser T J , de Greef W J 
Published: December 2004

Abstract
The reduced thyroid activity during short-term starvation is associated with a lowered hypothalamic synthesis and secretion of TRH. However, little is known about the cause of the reduced thyroid function during prolonged malnutrition. We have therefore studied the effects of food reduction to one-third of normal (FR33) on the hypothalamus-pituitary-thyroid axis of male and female Wistar rats. After 3 weeks body weights of FR33 rats were almost 50% lower than those of controls. In both sexes, FR33 caused marked increases in serum corticosterone, and decreases in serum TSH, thyroxine (T4), free T4, tri-iodothyronine (T3) and free T3. While the free T3 fraction (FFT3) in serum decreased, the free T4 fraction (FFT4) tended to increase. Electrophoretic analysis indicated that decreased FFT3 was correlated with an increased thyroxine-binding globulin, while the increase in FFT4 seemed due to a decreased thyroxine-binding prealbumin binding capacity. Total RNA and proTRH mRNA in the hypothalamus were not affected by FR33. Median eminence and posterior pituitary TRH content tended to increase in FR33 rats, suggesting that hypothalamic TRH release is reduced in FR33 rats. Anterior pituitary TSH content was decreased by FR33 in both sexes, but pituitary TSHβ mRNA and TRH receptor status were not affected except for increased pituitary TSHβ mRNA in female FR33 rats. Although FR33 had no effect on pituitary weight, pituitary RNA and membrane protein content in FR33 rats were 50–70% lower than values in controls.
In conclusion, prolonged food reduction suppresses the pituitary-thyroid axis in rats. In contrast to short-term food deprivation, the mechanism whereby serum TSH is suppressed does not appear to involve decreases in proTRH gene expression, but may include effects on pituitary mRNA translation. Our results further support the hypothesis that TSH release may be lowered by increased corticosterone secretion, although the mechanism of this effect may differ between acute starvation and prolonged food reduction.
Journal of Endocrinology (1996) 150, 169–178
Role of phosphoprotein phosphatases in the corpus luteum: II Control of progesterone secretion by isolated rat luteal cells
Authors: Abayasekara D R E , Ford S L , Persaud S J , Jones P M 
Published: December 2004

Abstract
The key role of protein kinases and protein phosphorylation in the regulation of luteal steroidogenesis is well documented. However the role of phosphoprotein phosphatases (PP) and dephosphorylation in the regulation of luteal cell progesterone secretion is as yet unknown. We have recently demonstrated the presence and activity of PP1 and PP2A in rat luteal cells and the present study was undertaken to determine the consequences of inhibiting PP activity in terms of progesterone secretion. Three structurally dissimilar inhibitors of PP1/2A, okadaic acid, calyculin A and cantharidin each caused a dose-dependent inhibition of LH-induced progesterone secretion without affecting cyclic AMP accumulation. The less potent derivative of okadaic acid, norokadaone, had no effect on either parameter, suggesting that the inhibitory actions on progesterone secretion are due to their specific actions on PP activity and that this inhibition occurs principally at a locus which is distal to the generation of cyclic AMP. In contrast to the inhibitory effects of PP1/2A inhibitors on progesterone biosynthesis, a PP2B inhibitor, cypermethrin, had no effect on LH-stimulated steroidogenesis. The three PP1/2A inhibitors also caused a concentration-dependent inhibition of dibutyryl cyclic AMP-stimulated progesterone secretion. However, none of the inhibitors affected 22R-hydroxycholesterol-supported steroidogenesis, clearly demonstrating that the inhibitors did not interfere with the activity of steroidogenic enzymes. These results suggest that cycles of phosphorylation/dephosphorylation of specific proteins are required for the sustained production of progesterone. Whilst the precise location and function of putative PP substrates is uncertain, the present results indicate that they are involved in regulating the availability of free cholesterol to steroidogenic enzymes within mitochondria.
Journal of Endocrinology (1996) 150, 213–221
Attenuation of human chorionic gonadotropin release by nitric oxide in choriocarcinoma cell lines
Authors:   Myat-Thanda, Histumoto Y , Saheki S , Kitagawa H , Yano J , Matsuura S 
Published: December 2004

Abstract
Nitric oxide (NO) is involved in the regulation of endocrine functions, but only a few studies have been reported about its role in placental hormone secretion. We investigated whether NO has any function in the release of human chorionic gonadotropin (hCG) in two different choriocarcinoma cell lines, JEG-3 and BeWo. First, nitric oxide synthase (NOS) was characterized in the choriocarcinoma cells. NOS activity was localized mainly in the particulate fraction and depended on calcium/calmodulin. Activity was inhibited by the presence of the l-arginine analog, NG-monomethyl-l-arginine (L-NMMA; 1 × 10−4 m). Western blot analysis showed that the choriocarcinoma cells contained an endothelial isoform of NOS.
The NO donor, sodium nitroprusside (SNP; 1 × 10−5 and 1 × 10−4 m), significantly inhibited hCG secretion in both choriocarcinoma cell lines. The suppression of hCG release by SNP (1 × 10−5 m) was blocked by the addition of an NO scavenger, hemoglobin (1 × 10−6 m). l-Arginine (1 × 10−2 m), a NOS substrate, inhibited basal hCG secretion in JEG-3 cells. Incubation of the cells with L-NMMA (1 × 10−4 and 1 × 10−3 m) significantly increased hCG release. Exposure of both cell lines to increasing concentrations of a cyclic GMP analog (8-bromo-cyclic GMP; 1 × 10−4 to 1 × 10−2 m) caused a dose-dependent inhibition of hCG release. Cyclic GMP accumulation in response to SNP (1 × 10−4 m), however, was not detected in either JEG-3 or BeWo cells. These data demonstrated that the endothelial isoform of NOS and a functional l-arginine-NO pathway are present in the choriocarcinoma cell lines. In addition, these findings support the hypothesis that NO produced in these cell lines is involved in the regulation of hCG secretion. We assume that although cyclic GMP is likely to play a role as a second messenger, a cyclic GMP-independent pathway cannot be excluded as a possible physiological mechanism in the attenuation of hCG release by NO.
Journal of Endocrinology (1996) 150, 243–253
Stimulation of creatine kinase specific activity in human osteoblast and endometrial cells by estrogens and anti-estrogens and its modulation by calciotropic hormones
Authors: Fournier B , Häring S , Kaye A M , Sömjen D 
Published: December 2004

Abstract
We have previously demonstrated sex-specific stimulation of creatine kinase specific activity (CK) in bone cells both in vivo and in vitro, in primary culture cells derived from rat and human bone and in established human bone-derived cell lines. We found that the female-derived cell line, SaOS-2, responded to 17β-estradiol (E2) by increased CK specific activity. The effects of E2 on the CK activity in SaOS-2 cells was inhibited by 100-fold excess of 4-hydroxytamoxifen (Tam) as well as by the other anti-estrogen, ICI 164,384. Tam by itself had some stimulatory effect whereas ICI 164,384 showed no estrogenic activity. We also demonstrated the estrogenic-like effect of another anti-estrogen, raloxifene (Ral), which is agonist only in the SaOS-2 osteoblast-like cells but not in the human endometrial, Ishikawa cell line. Ishikawa cells respond to E2 and to Tam by increased CK activity. In both osteoblasts and endometrial cell lines, Ral and Tam were inhibitory in the presence of E2. The effects of E2 on SaOS-2 cells are at least partially mediated by the estrogen receptor (ER) at the level of transcription as demonstrated by transient transfection experiments using the human creatine kinase promoter chloramphenicol acetyltransferase in these cells.
Pretreatment of SaOS-2 with calcitropic hormones, either 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) or human parathyroid hormone (1–34) (hPTH(1–34)) increased the stimulation of CK by E2 by 40–60% relative to E2 alone and significantly increased the sensitivity of the cells to E2 by lowering the effective hormonal dose needed for stimulation of CK by E2 by 100-fold. This stimulatory effect of pretreatment of the cells with 1,25(OH)2D3 was due to a 2·5-fold increase in the level of ER expression as measured directly by enzyme immunoassay in the SaOS-2/1 subline. The increase in the responsiveness to E2 by hPTH(1–34) was not due to an increase in ER level in the cells. We can conclude that in cell cultures as in vivo, Ral shows different effects depending on the cell type, namely estrogenic-like activity in skeletal cells but not in uterine cells. We can also conclude that as with rat-derived cells, in bone cells derived from human bone 1,25(OH)2D3 increased the sensitivity to E2 due to an increase in the number of ER in the cells, whereas PTH(1–34) augmented the response to E2 without increasing ER, by another, as yet unknown, mechanism. These studies suggest that the treatment of pathological bone disorders may be improved by combined hormone therapy.
Journal of Endocrinology (1996) 150, 275–285
Evolution of growth hormone neurosecretory disturbance after cranial irradiation for childhood brain tumours: a prospective study
Authors: Spoudeas H A , Hindmarsh P C , Matthews D R , Brook C G D 
Published: December 2004

Abstract
To determine the aetiopathology of post-irradiation growth hormone (GH) deficiency, we performed a mixed longitudinal analysis of 56 24 h serum GH concentration profiles and 45 paired insulin-induced hypoglycaemia tests (ITT) in 35 prepubertal children, aged 1·5–11·8 years, with brain tumours in the posterior fossa (n=25) or cerebral hemispheres (n = 10). Assessments were made before (n = 16), 1 year (n = 25) and 2 to 5 years (n = 15) after a cranial irradiation (DXR) dose of at least 30 Gy. Fourier transforms, occupancy percentage, first-order derivatives (FOD) and mean concentrations were determined from the GH profiles taken after neurosurgery but before radiotherapy (n = 16) and in three treatment groups: Group 1: neurosurgery only without DXR (n = 9); Group 2: ≥30 Gy DXR only (n = 22); Group 3: ≥30 Gy DXR with additional chemotherapy (n = 9). Results were compared with those from 26 short normally growing (SN) children.
Compared with SN children, children with brain tumours had faster GH pulse periodicities (200 min vs 140 min) and attenuated peak GH responses to ITT (24·55 (19·50–30·20) vs 8·32 (4·57–15·14) mU/I) after neurosurgery, before radiotherapy. However, spontaneous GH peaks (19·05 (15·49–23·44) vs 14·13 (9·12–21·38) mU/l), 24 h mean GH (5·01 (4·37–5·62) vs 3·98 (2·63–5·89) mU/l) and FODs (1·43 (1·17–1·69) vs 1·22 (0·88–1·56) mU/l per min) were similar. The abnormalities present before radiotherapy persisted in group 1 children at 1 year when 24 h mean GH (2·45 (1·17– 5·01) mU/l) and FODs (0·73 (0·26–1·20) mU/l per min) were additionally suppressed, although partial recovery was evident by 2 years.
With time from radiotherapy, there was a progressive increase in GH pulse periodicity (Group 2: 200 min at 1 year, 240 min at ≥2 years; Group 3: 140 min at 1 year, 280 min at ≥2 years) and a decrease in 24 h mean GH (Group 2 vs Group 3 at ≥2 years: 2·45 (1·70–3·47) vs 1·86 (1·32–2·69) mU/l) and FODs (Group 2 vs Group 3 at ≥2 years; 0·56 (0·44–0·69) vs 0·44 (0·27–0·61) mU/l per min). Initial discrepancies between measures of spontaneous and stimulated (ITT) GH peaks were lost by 2 or more years (spontaneous vs ITT; Group 2: 7·76 (5·89–9·77) vs 3·80 (0·91–15·84) mU/l; Group 3: 6·03 (4·27–8·32) vs 3·80 (0·31–46·77) mU/l).
After cranial irradiation, a number of changes evolved within the GH axis: faster GH pulse periodicities and discordance between physiological and pharmacological tests of GH secretion before irradiation gave way to a slow GH pulse periodicity, decreased GH pulse amplitude and rate of GH change (FOD) and, with time, eventual concordance between physiological and pharmacological measures. The evolution of these disturbances may well reflect differential pathology affecting hypothalamic GH-releasing hormone and somatostatin.
Journal of Endocrinology (1996) 150, 329–342