bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel approach to assess changes in endocrine secretion: analysis of GnRH antagonist (Nal-Glu) suppression of gonadotropin release in ovariectomized ewes
Authors: Normolle Daniel P , Evans Neil P , Dahl Geoffrey E , Padmanabhan Vasantha 
Published: December 2008

Abstract
Circulating hormone levels reflect the outcome of multiple feedback systems. A method to accurately assess the dynamics of hormonal changes in samples collected at infrequent intervals and compare these dynamic processes among treatment groups is presented. In this approach, a smooth curve is fitted to each time series of concentrations produced in an experiment, the curves are summarized by numerical measurements, and the measurements are subjected to statistical analysis. The method is demonstrated on data from an experiment that explores the differential effects of a competitive GnRH receptor antagonist (Nal-Glu) on circulating levels of LH and FSH.
In this experiment, six adult ovariectomized Suffolk ewes were treated with one of three doses of Nal-Glu using a crossover design. LH and FSH concentrations were determined in hourly samples of jugular blood for 24 h after treatment. Applying the analytical approach, we observed differential effects of increasing concentrations of Nal-Glu on circulating LH and FSH concentrations. The magnitude of LH suppression was similar from dose to dose, while the duration of LH suppression was dose-dependent. In contrast, all doses of Nal-Glu elicited similar effects on the amplitude, duration and time to recovery of FSH suppression. Studies conducted in vitro utilizing dispersed ovine pituitary cells in culture demonstrated that the differential effects of Nal-Glu on FSH and LH secretion were not the outcome of differential sensitivity of FSH and LH to GnRH. The differential effects of Nal-Glu on circulating LH and FSH concentrations may be due to a number of factors, including other releasing or release-inhibiting hormones, paracrine modulators involved in selective regulation of FSH, and/or differences in clearances.
European Journal of Endocrinology 136 519–530
Oxytocin-induced changes in single cell K+ currents and smooth muscle contraction of guinea-pig gastric antrum
Authors: Duridanova Dessislava B , Nedelcheva Milena D , Gagov Hristo S 
Published: December 2008

Abstract
To study the effects of oxytocin on both spontaneous phasic contractions and K+ outward currents (IK) of the so-called 'non-target' smooth muscle cells, physiological concentrations of oxytocin ranging between 10−12 mol/l and 10−8 mol/l were applied to smooth muscle preparations and single voltage-clamped cells isolated from the circular layer of the guinea-pig gastric antrum. Oxytocin (10−12mol/l to 10−8 mol/l) suppressed, in a dose-dependent manner, the tetrodotoxin- and atropine-resistant spontaneous phasic contractions and shifted rightward the dose–response curves of 10−7 mol/l charybdotoxin and 10−3mol/l BaCl2. In cells with preloaded intracellular Ca2+ stores, oxytocin (10−12 mol/l to 10−9 mol/l) caused a dose-dependent activation of the charybdotoxin-blockable non-inactivating component of IK (IK(s1)) of single voltage-clamped cells, which was accompanied by hyperpolarization of the cell membranes. 8Lys-vasopressin and 8arg-vasopressin failed to mimic the effects of oxytocin on both contraction and K+ currents. Further, the oxytocin-induced activation of IK(s1) was effectively antagonized by 5× 10−8 mol/l U-73122 or 5× 10−6 mol/l 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (inhibitors of the cell membrane phospholipase C), as well as by intracellularly applied heparin (selective inhibitor of inositol-1,4,5-trisphosphate (IP3)-induced Ca2+ release channels). In cells incubated in the absence of Ca2+ entry throughout the study, oxytocin (10−9 mol/l) caused a slight and transient increase of IK(s1) amplitudes. Neither ryanodine (10−6 mol/l nor cyclopiazonic acid (10−6 mol/l) were able to restore the IK-activating effect of oxytocin in these cells.
The data obtained suggest (i) that selective oxytocin receptors are present on the membranes of guinea-pig antral smooth muscle cells, (ii) that the oxytocin-related relaxation may result from the activation of Ca2+-sensitive K+ conductivity via activation of IP3-induced release of Ca from the submembrane located cisternae of the sarcoplasmic reticulum Ca2+ stores and (iii) in turn, this evokes a non-inactivating component of IK, hyperpolarizing the cell membrane.
European Journal of Endocrinology 136 531–538
Carbamoylcholine regulation of polyphosphoinositide synthesis and hydrolysis in cultured, dispersed, digitonin-permeabilized mouse pancreatic islet cells
Authors: Kardasz Andrew M , Thams Peter , Capito Kirsten , Hedeskov Carl J 
Published: December 2008

Abstract
Continuing formation of inositol phosphates during stimulation of pancreatic β-cells by hormones and neurotransmitters requires the continued synthesis of the polyphosphoinositides phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5 bisphosphate (PIP2) from phosphatidylinositol (PI). In the present study we have investigated how this pathway and the activity of phosphoinositide-specific phospholipase C (PI-PLC) are regulated by carbamoylcholine (CCh), Ca2+, the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), GTPγS and NaF in 44-h [3H]inositol-labelled, dispersed and digitonin-permeabilized mouse pancreatic islet cells.
CCh stimulated not only PI-PLC (G-protein-mediated) but also, by an as yet unknown mechanism, significantly enhanced PI 4-kinase activity, estimated as the PIP:PI ratio, by 100%, and further increased the flux from PI to PIP and PIP2. GTPγS and NaF mimicked the effects of CCh on PI-PLC but had no effect on the levels of PIP and PIP2. TPA raised the PIP:PI ratio by 75%. In addition TPA counteracted the CCh stimulation of PI-PLC. There was no effect of 10−6 mol/l Ca2+ on the levels of PIP and PIP2. Experiments with quinacrine and adenosine confirmed that PI-PLC and PI 4-kinase could be regulated independently of each other. In conclusion, these data point to differential regulation of polyphosphoinositide synthesis and breakdown.
European Journal of Endocrinology 136 539–545
Effect of natural menopause on serum levels of IGF-I and IGF-binding proteins: relationship with bone mineral density and lipid metabolism in perimenopausal women
Authors: Nasu Masamichi , Sugimoto Toshitsugu , Chihara Mieko , Hiraumi Mitsuo , Kurimoto Fumihiko , Chihara Kazuo 
Published: December 2008

Abstract
The present study was performed to examine the effect of natural menopause on serum levels of IGF-I, IGF-binding protein (IGFBP-2) and -3 as well as on bone mass and lipid metabolism in perimenopausal women. One hundred and twenty-one healthy Japanese women, who were 45–55 years old, were studied (71 premenopausal and 50 postmenopausal women 1–9 years after menopause). Bone mineral density (BMD) was measured at the middle third of the radius by using dual energy X-ray absorptiometry. Serum levels of IGF-I, but not those of IGFBP-2 or -3, were significantly reduced in the postmenopausal group compared with the premenopausal group. One year after menopause, serum IGF-I levels were significantly lower, and the biochemical markers of bone turnover, such as serum total alkaline phosphatase level and urinary calcium to creatinine ratio, were significantly higher than the premenopausal levels. Serum levels of IGF-I, but not those of IGFBP-2 or-3, were positively correlated with BMD. Serum levels of IGFBP-2, but not those of IGF-I or IGFBP-3, were negatively correlated with body mass index and body weight. Finally, serum levels of IGFBP-3, but not those of IGF-I, were positively correlated with serum levels of total cholesterol and triglyceride. The present findings suggest that a rapid decrease in serum IGF-I levels after menopause might be partly involved in bone loss following gonadal failure and that IGFBP-2 and -3 might be related to the regulation of body mass and lipid metabolism during perimenopause respectively, although the mechanisms remain unknown.
European Journal of Endocrinology 136 608–616
Ovarian 17α-hydroxyprogesterone responses to GnRH analog testing in oligomenorrheic insulin-dependent diabetic adolescents
Authors: Virdis Raffaele , Zampolli Maria , Street Maria E , Vanelli Maurizio , Potau Neus , Terzi Cesare , Ghizzoni Lucia , Ibanez Lourdes 
Published: December 2008

Abstract
Objective: To investigate the pituitary-ovarian function in adolescent girls with insulin-dependent diabetes mellitus (IDDM).
Design: Clinical case-control study.
Methods: The GnRH analog leuprolide acetate was administered subcutaneously to 16 adolescents with IDDM (seven eumenorrheic and nine oligomenorrheic) and 13 controls between 0800 and 0900 h. Blood samples were collected at baseline and 0·5, 3, 6 and 24 h after leuprolide to measure levels of gonadotropins, 17α-hydroxyprogesterone (17-OHP), androgens and estradiol.
Results: Mean baseline serum LH levels were significantly higher in eumenorrheic compared with oligomenorrheic IDDM patients, while peak LH responses to GnRH analog testing were similar in all subjects. Oligomenorrheic IDDM girls showed, as a group, a distinct 17-OHP response to GnRH analog stimulation, which in five out of nine girls was in the range of functional ovarian hyperandrogenism (≥ 8·6 nmol/l). Androgen and estradiol levels were not significantly altered in any group. No correlation was found between steroid levels and HbA1c levels, although the latter were significantly higher in oligomenorrheic than in eumenorrheic patients.
Conclusion: About 50% of the oligomenorrheic IDDM adolescents had an increased ovarian 17-OHP response to GnRH analog stimulation in the range of functional ovarian hyperandrogenism. Factors other than metabolic control, such as stress, may play an etiologic role in IDDM ovarian dysfunction.
European Journal of Endocrinology 136 624–629
Melatonin receptors are present in adult rat Leydig cells and are coupled through a pertussis toxin-sensitive G-protein
Authors: Valenti Sandra , Giusti Massimo , Guido Roberta , Giordano Giulio 
Published: December 2008

Abstract
Previous studies have suggested that melatonin (MLT) acts directly on rat Leydig cells by modulating androgen production. In the present study, the site of action of MLT was investigated. The binding of 2-[125I]iodomelatonin (125I-MLT; 7–240 pmol/l) to Leydig cell membrane fragments was tested in the presence or absence of guanosine 5′-O-(3-thiotriphosphate) (GTP-γ-S; 50 μmol/l). Saturation studies and Scatchard analysis revealed the existence of a high-affinity binding site with a Bmax of 46·70± 3·50 fmol/mg protein and a Kd of 88·70±6·20 pmol/l; treatment with GTP-γ-S reduced the concentration of 125I-MLT binding sites (Bmax 34·03±4·50), while increasing the Kd to 106·5± 2·61 pmol/l.
Pretreatment of the cells with pertussis toxin (PTX; 10 ng/ml for 16 h) resulted in a decreased binding of I-MLT and a lack of effect of GTP-γ-S. Moreover, the effect of MLT on testosterone secretion induced by LH (30 mIU/ml), forskolin (1 μmol/l) and LHRH (100 nmol/l) was studied after 3-h incubation of cells which had been precultured with or without PTX. The inhibition of testosterone secretion due to MLT administration was eliminated by PTX pretreatment during forskolin and LH, but not during LHRH administration. However, 17-hydroxyprogesterone levels were higher in all groups incubated in the presence of MLT, irrespective of PTX pretreatment.
Our data suggest that: (a) MLT receptors are present on the membranes of adult rat Leydig cells; (b) they couple through PTX-sensitive G-protein-coupled binding sites; (c) the mechanism by which MLT blocks 17–20 desmolase enzymatic activity (thus leading to increased 17-hydroxyprogesterone levels), and testosterone secretion during LHRH stimulation is likely to depend on one or more different mechanism(s) of action.
European Journal of Endocrinology 136 633–639
Expression of parathyroid hormone-related peptide (PTHrP) and PTH/PTHrP receptor in newborn human calvaria osteoblastic cells
Authors: Lomri Abderrahim , de Pollak Cindy , Sebag Michael , Goltzman David , Kremer Richard , Marie Pierre J 
Published: December 2008

Abstract
We examined the expression of parathyroid hormone-related peptide (PTHrP) and its receptor in normal newborn human calvaria osteoblastic (NHCO) cells. Northern blot analysis showed that NHCO cells express a single 1·6 kb transcript of PTHrP, which was increased within 1 h (2x) and peaked at 6 h (7x) after serum treatment. In the culture media, the release of PTHrP peptide was maximally increased (4x) 24 h after the addition of serum, as determined by immunoradiometric assay. NHCO cells exhibited a cytoplasmic immunostaining for PTHrP in the presence of serum, and most PTHrP-positive cells were alkaline phosphatase-negative, suggesting that PTHrP was expressed in undifferentiated cells. Furthermore, RT-PCR analysis showed that both PTHrP and PTH/PTHrP receptor were expressed in NHCO cells in basal conditions or after stimulation with serum. The maximal PTHrP expression induced by serum suppressed PTH/PTHrP receptor expression, suggesting that PTHrP down-regulated its receptor in NHCO cells. Treatment with 10 nm human PTH(1–34—which binds to PTH/PTHrP receptors, increased intracellular cAMP levels and alkaline phosphatase activity, and decreased cell growth, indicating that ligand binding to PTH/PTHrP receptors regulates NHCO cell proliferation and differentiation. The expression and synthesis of PTHrP and the presence of functional PTH/PTHrP receptors suggest a possible paracrine mechanism of action of PTHrP in normal human calvaria osteoblastic cells.
European Journal of Endocrinology 136 640–648
Epidermal growth factor receptor expression in patients with ductal breast carcinoma. Comparison with clinicopathological factors and estrogen receptor status
Authors: Harlozinska A , Bar J K , Bebenek M , Kowalski P , Sedlaczek P 
Published: December 2008

ABSTRACT
Epidermal growth factor receptor (EGFR) and estrogen receptor (ER) status were immunohistochemically evaluated in 80 primary ductal breast carcinomas. The comparison between EGFR status and tumor grading, tumor size, lymph node involvement and age of patients was performed. EGFR expression was found in 87.5% of carcinoma samples and 46.3% of tumors were positive for ER staining. The inverse relationship between EGFR and ER expression was confirmed and it was evident that a high concentration of EGFR exceeding 25% of a tissue section may inhibit or significantly limit the ability to express ERs. EGFR presence was significantly associated with poorly differentiated tumors. No correlation was found between EGFR positivity and tumor size, lymph node involvement or age of patients. Our results indicate that EGFR status does not seem to be a valuable independent prognostic indicator, but that the combination of EGFR positivity (above 25% of a tissue section) accompanied by a low or undetectable level of ER expression should be considered as a potential marker of a poor prognosis in patients with ductal breast carcinoma.
Quantitative in-situ hybridization histochemistry studies on growth hormone (GH) gene expression in acromegalic somatotrophs: effects of somatostatin, GH-releasing factor and cortisol
Authors: Levy A. , Lightman S. L. 
Published: December 2008

ABSTRACT
We have examined the effects of human GH-releasing factor (1–44) (GRF), cortisol and somatostatin-(1–14) on GH gene expression in solid tissue and dispersed cells from human pituitary adenomas using quantitative in-situ hybridization histochemistry. Sections cut from tissue obtained at hypophysectomy from three acromegalic patients were hybridized to probes directed against mature α-subunit, GH, prolactin, pro-opiomelanocortin, TSHβ-subunit and LHβ-subunit mRNA. Only one biopsy contained GH mRNA in isolation. A second was found to co-exhibit GH, prolactin and α-subunit mRNA, and a third was found to contain prolactin, TSHβ-subunit, α-subunit and LHβ-subunit mRNA, with GH mRNA below the limit of specific detection, indicating that the sample was composed of normal rather than adenomatous pituitary tissue. GH mRNA in individual dispersed cells derived from the latter declined to barely detectable levels over 287 h, both in cultures containing GRF (10 ng/ml) or GRF (10 ng/ml) plus somatostatin (10 ng/ml) and in controls, but increased fourfold in cultures containing GRF (10 ng/ml) plus cortisol (0·5 μmol/l). GH mRNA remained unchanged in both adenoma samples over 138 and 450 h, irrespective of the addition of GRF or GRF plus hydrocortisone. In these samples, somatostatin plus GRF had no consistent effect. These studies confirm that quantitative in-situ hybridization histochemistry can be used to investigate hormone gene regulation in small samples of human tissue and should enable us to define more clearly the level at which abnormal gene regulation occurs.
Regulation of LH subunit mRNA levels by gonadal hormones in female rats
Authors: Abbot S. D. , Docherty K. , Clayton R. N. 
Published: December 2008

ABSTRACT
To determine the physiological role of the ovaries in regulation of LH subunit gene expression, levels of cytoplasmic mRNA were measured in a cDNA-RNA dot-blot hybridization assay. An increase (twofold) in α mRNA was first detected 8 days after ovariectomy and then remained stable for 4 weeks. In contrast, LH-β mRNA increased by 60–79% within 12 h of removing the ovaries and then rose progressively to six times the intact values at 3 and 4 weeks. Increases in LH-β mRNA were always greater than those of α mRNA. Oestradiol, and oestradiol plus progesterone, but not progesterone alone, prevented the rise in α and LH-β mRNA 10 days after ovariectomy.
Three days after ovariectomy, α mRNA, but not LH-β mRNA, was suppressed to below intact control values by oestradiol and oestradiol plus progesterone, indicating greater sensitivity of α mRNA to oestradiol inhibition at this stage. A single injection of oestradiol (1 μg s.c.) to rats ovariectomized 14 days previously transiently suppressed α and LH-β mRNA levels and serum LH concentrations in parallel for 1–8 h, after which high preinjection values were restored. However, pituitary LH content remained suppressed after LH mRNA levels had returned to the control values of ovariectomized rats.
In most instances there was a qualitative positive correlation between changes in α and LH-β mRNA, pituitary LH content and serum LH concentrations. LH content reflected LH-β mRNA changes more closely than those of α mRNA. However, in oestradiol-treated rats ovariectomized 10 days previously, LH content remained increased despite normalization of the LH-β and α mRNA levels, suggesting differential sensitivity to oestradiol of the gene expression and translational processes. Thus divergence of pre- and post-translational regulation of LH biosynthesis was demonstrated. These results imply an important physiological role for female sex hormones in the control of LH gene expression and LH biosynthesis.
Prolactin mRNA fell by 30–50% for the first 2 weeks after ovariectomy, but by 3 and 4 weeks values were similar to those of intact controls. Serum and pituitary prolactin levels were reduced by 50% or more at all time-points, despite normalization of mRNA. Treatment of ovariectomized rats for 10 days with oestradiol and progesterone, either alone or combined, reversed the fall in prolactin mRNA and serum and pituitary prolactin levels. These changes in prolactin gene expression and synthesis were opposite to those of LH subunits in response to the same in-vivo hormone manipulations.
Growth hormone mRNA levels were unchanged by ovariectomy, oestradiol or progesterone treatment. Levels of TSH-β mRNA increased slightly (maximum up to 50%) after ovariectomy, but were unaltered by oestradiol and progesterone treatment for 10 days. These results support the view that α mRNA changes, resulting from ovariectomy, oestradiol and progesterone treatment, occur in gonadotrophs and not thyrotrophs, which also express the α subunit gene.
Effects of l-leucine, its 2-keto acid metabolite and its nonmetabolized analogue on rat tumoral islet cell function
Authors: Leclercq-Meyer V. , Marchand J. , Sener A. , Blachier F. , Malaisse W. J. 
Published: December 2008

ABSTRACT
l-Leucine and 2-ketoisocaproate stimulated insulin release from perifused rat tumoral islet cells (RINm5F line). The secretory response coincided with an increase in the intracellular ATP/ADP ratio, a stimulation of 45Ca outflow from cells perifused in the presence of extracellular Ca2+, and an increase in 32P efflux from cells prelabelled with radioactive orthophosphate. In contrast to d-glucose, however, l-leucine or 2-ketoisocaproate failed to decrease 86Rb outflow, to inhibit 45Ca outflow from cells perifused in the absence of Ca2+ and to enhance the labelling of inositol-containing phospholipids in cells exposed to myo-[2-3H]inositol. These findings suggest that d-glucose, l-leucine and 2-ketoisocaproate exert dissimilar effects on the subcellular distribution of adenine nucleotides and/or 86Rb. The nonmetabolized analogue of l-leucine, 2-aminobicyclo-[2.2.1]heptane-2-carboxylic acid (BCH), also caused an initial stimulation of insulin release and 32P efflux, but this was soon followed by a severe and irreversible inhibition of insulin output, associated with a permanent enhancement of 86Rb outflow. The dual ionic and secretory response to BCH is interpreted in the light of its dual effect on the catabolism of endogenous amino and fatty acids, and raises the view that BCH could be used to interfere with the function of insulinoma cells.
Oestrogen receptor mRNA and a related RNA transcript in mouse ovaries
Authors: Hillier S.G. , Saunders P.T.K. , White R. , Parker M.G. 
Published: December 2008

ABSTRACT
Oestrogen receptor mRNA expression in mouse ovaries was analysed by Northern blotting of total RNA using 32P-labelled RNA probes complementary to different functional domains of the oestrogen receptor. The ~6·5 kb mouse oestrogen receptor mRNA transcript was present in immature and adult ovaries at extremely low abundance compared with uterus and oviduct. Using a probe complementary to the steroid-binding domain of the oestrogen receptor (probe EF), a novel RNA transcript of ~1·5 kb was also found in the ovaries but was absent from uterus and oviduct. The melting temperature of the hybrid produced by the ~1·5 kb transcript with probe EF was ~10°C lower than that produced by authentic oestrogen receptor mRNA, which demonstrates incomplete sequence homology between the two transcripts and indicates that the ~1·5 kb RNA is not a truncated form of oestrogen receptor mRNA. Furthermore, the ~1·5 kb RNA lacks the DNA-binding domain found in the oestrogen receptor. The ~1·5 kb RNA, but not oestrogen receptor mRNA, was enriched in total RNA from isolated granulosa cells compared with residual ovarian tissue. The encoded product of this novel oestrogen receptor-related RNA could be a steroid-binding protein involved in oestrogen action in the ovaries.