bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of exogenous growth hormone pretreatment on the pituitary growth hormone response to growth hormone-releasing hormone alone or in combination with pyridostigmine in Type I diabetic patients
Authors: Giustina Andrea , Bossoni Simonetta , Bodini Corrado , Cimino Antonino , Pizzocolo Giuseppe , Schettino Maurizio , Wehrenberg William B. 
Published: June 2009

Abstract.
We evaluated the effects of iv pretreatment with exogenous GH on the GH response to GHRH either alone or in combination with pyridostigmine in 14 Type I diabetic patients and 6 normal subjects. All the subjects received an iv bolus injection of biosynthetic human GH, 2 IU; 2 h later they received either a. pyridostigmine, 120 mg orally, or b. placebo, 2 tablets orally, followed 1 h later by iv injection of GHRH(1-29) NH2, 100 μg. In normal subjects the median GH peak after GH+GHRH was 1.8, range 1.2-6.9 μg/l. Pyridostigmine enhanced the GH response to GHRH in all subjects. The median GH peak after pyridostigmine+ GH+GHRH was 32.7, range 19.8-42.1 μg/l (p<0.001 vs GHRH alone). Seven diabetic subjects had median GH peaks after GH+GHRH >6.9 μg/l (the maximum GH peak after GH+GHRH in normal subjects) (group A: median GH peak 35.7, range 21.7-55 μg/l). The other diabetic subjects had GH peak lower than 6.9 μg/l (group B: median GH peak 4.4, range 2.1-6.5 μg/l). Pyridostigmine significantly increased the GH response to GHRH in group B patients (median GH peak 29.3, range 15.7-93.4 μg/l, p<0.001 vs GH+GHRH alone), but not in group A patients (median GH peak 39.9, range 21.9-64.9 μg/l). Group A diabetic patients were younger and had higher HbA1c and blood glucose levels than group B patients. In those diabetic patients with an exaggerated GH response to GH+GHRH, pyridostigmine failed to cause the increase in GH secretion observed in diabetic and control subjects with no responses to GH+GHRH. It can be suggested that elevated 24-h GH levels in some Type I diabetic patients may be due to decreased somatostatinergic tone which in turn causes altered autoregulation of GH secretion. We hypothesize that this finding is a consequence of a reset of the hypothalamic control of GH secretion caused by a chronically elevated blood glucose level in this subpopulation.
On the role of the peptide galanin in regulation of growth hormone secretion
Authors: Hulting Anna-Lena , Meister Björn , Carlsson Lena , Hilding Agneta , Isaksson Olle 
Published: June 2009

Abstract.
The effects of the peptide galanin on growth hormone secretion were studied in vitro using cultured rat and human anterior pituitary cells, and in vivo by iv administration of galanin in both rats and humans. Galanin in concentrations from 10 nmol/l to 1 μmol/l did not alter basal GH release, but slightly inhibited GHRH-stimulated GH release from cultured rat anterior pituitary cells. Galanin (1 μmol/l) did not significantly change basal or GHRH-stimulated GH secretion from cultured human anterior pituitary cells. In contrast, iv injection of 1 μg (300 pmol) galanin to rats induced an increase in plasma GH that was reproducible at repetitive injections. The galanin-induced GH release in rats was of a lower magnitude than the increase in plasma GH after iv injections of GHRH, and was seen with a 5-15 min delay in comparison to iv administered GHRH. In man, iv infusions of galanin (40 pmol ·kg−1 · min−1 · (40 min)) also caused a significant increase in plasma GH, but it occurred 25-30 min after the beginning of the infusion. These results suggest an indirect action of galanin on GH release in both rats and humans, i.e. galanin does not directly affect the somatotropes. In agreement with a central action, no binding sites for galanin could be demonstrated in the rat anterior pituitary by autoradiography. Since galanin did not affect somatostatin release from fragments of rat mediobasal hypothalamus, the stimulatory effects of galanin on GH release are most likely mediated via a stimulatory effect on GHRH neurons.
Biosynthesis of 16-androstene steroids and testosterone by porcine testis tissue in vitro: effect of age and relationships with fat 5α-androstenone levels in vivo
Authors: Louveau Isabelle , Bonneau Michel , Gower D. B. 
Published: June 2009

Abstract.
The relationships between testicular 16-androstene and testosterone formation in young pigs and levels of 5α-androstenone in fat exhibited at older ages were investigated. Testis tissue samples were taken from Large White male pigs at 75, 100 and 125 days of age (8 pigs per age group) and incubated with a mixture of [3H]progesterone and [14C]pregnenolone. 5α-androstenone levels in fat were measured in all 24 pigs at 125, 145 and 170 days of age. Less androstadienone, more 3α-androstenol and 11-fold more 3β-androstenol + androstadienol were synthesized from pregnenolone than from progesterone. 5α-androstenone synthesis increased significantly between 100 and 125 days, whereas that of androstadienone declined between 75 and 100 days of age. Litter had a significant effect on all 16-androstene rates of formation. Fat 5α-androstenone levels were positively correlated with 5α-androstenone formation from both precursors. They were correlated with 3β-androstenol + androstadienol (positively) and testosterone (negatively) rates of synthesis from progesterone. It is concluded that in vitro measurements of 5α-androstenone formation by testis tissue could be used as an early predictor of fat 5α-androstenone levels exhibited at older ages.
Balb/C mice immunized with either xenogeneic or syngeneic TSH produce immunoglobulins with anti-TSH and thyroid-stimulating activities
Authors: Ben-David Chava , Gafny Mira , Sirkis Nava , Gordon Amirav , Gross Jack 
Published: June 2009

Abstract.
Balb/C mice were immunized with bTSH (xenogeneic TSH) or extracts of Balb/C pituitaries (containing syngeneic TSH), either intracutaneously with Freund's adjuvant or intrasplenically. After bTSH, all blood samples contained anti-TSH antibodies. Thyroid-stimulating activity was assayed on FRTL-5 cells. Of 80 sera from immunized mice, 33 induced an increase in 99mTcO4 uptake, and 31/79 induced an increase in thyroidal 3[H]thymidine uptake by thyrocytes. With syngeneic TSH, anti-TSH antibodies were found in 10/19 mice. Immunoglobulins increasing thyrocyte technetium uptake were found in 14/19 mice, and immunoglobulins that stimulated thymidine uptake in thyrocyte DNA were detected in 12/19 sera. After immunization with both types of TSH, sera of some mice showed only one of the two bioactivities. Hybridomas were prepared with splenic lymphocytes of the mice immunized with either of the TSH preparations. These secreted TSH-binding immunoglobulins or immunoglobulins which stimulated thymidine or technetium uptake by the thyrocytes. One of the hybridomas from mice immunized with pituitary extract secreted a monoclonal antibody which stimulated thyroidal thymidine uptake, but inhibited bTSH-induced 99mTcO4 uptake. These findings might suggest that the anti-idiotypic network acting on TSH as an antigen could be involved in the pathogenesis of stimulatory antibodies in thyroid disease.
Insulin-like growth factor II and transforming growth factor β1 regulate insulin-like growth factor I secretion in mouse bone cells
Authors: Tremollieres Florence A. , Strong Donna D. , Baylink David J. , Mohan Subburaman 
Published: June 2009

Abstract.
Bone cells in culture produce and respond to growth factors, suggesting that local as well as systemic factors regulate bone volume. Previous studies have shown that IGF-I is the major mitogen produced by mouse bone cells and that its production is regulated by systemic agents such as PTH and estrogen. Because IGF-II and transforming growth factor β1 have been shown, respectively, to increase and decrease MC3T3-E1 cell proliferation, we tested the hypothesis that these two growth factors modulate the production of IGF-I in this cell line. In order to eliminate artifacts owing to IGF binding proteins, conditioned media samples were pretreated with IGF-II before measurement of IGF-I by RIA. After 24 h treatment at a density of 2.5× 104 cells/cm2, IGF-II (10 μg/l) induced a 2.2-fold increase compared with untreated control (9.5±1.5 vs 4.2±0.44 pg/μg protein, p<0.001), whereas transforming growth factor β1 (1 μg/l) caused a 66% decrease in IGF-I production (1.5±0.3 vs 4.2±0.44 pg/μg protein, p<0.001). Both IGF-II and transforming growth factor β1 regulated IGF-I production in a dose-, time- and cell density-dependent manner. The lowest effective doses for IGF-II and transforming growth factor β1 were 1 and 0.01 μg/l, respectively. These results support a role for IGF-II and transforming growth factor β1 as potent modulators of IGF-I secretion in mouse bone cells. Furthermore, regulation of IGF-I production in bone cells by IGF-II and transforming growth factor β1 in an autocrine/paracrine manner could represent a component part of the mechanism whereby the skeleton locally adapts in reponse to external stimuli.
Comparative effects of chronic administration of the non-steroidal antiandrogens flutamide and Casodex on the reproductive system of the adult male rat
Authors: Chandolia Ramesh K. , Weinbauer Gerhard F. , Simoni Manuela , Behre Hermann M. , Nieschlag Eberhard 
Published: June 2009

Abstract.
The effects of chronic blockade of androgen action by the antiandrogens flutamide and Casodex on serum and pituitary concentrations of LH and FSH, serum and testicular androgen levels, reproductive organ weights, and on spermatogenesis were compared in the adult rat. Animals were treated for 3 and 8 weeks with vehicle, Casodex (20 mg · kg−1 · (day)−1, flutamide (20 mg · kg−1 · (day)−1) and GnRH antagonist (150 μg/day, Detirelix). Treatment with GnRH antagonist suppressed gonadotropin and testosterone production, reduced the weights of testes, epididymides and seminal vesicles, and inhibited germ cell development. Flutamide administration markedly elevated serum and pituitary levels of gonadotropins as well as serum and testicular androgen concentrations. Casodex-induced elevation of gonadotropin concentrations was less pronounced and serum and testicular levels of androgens did not change significantly. The reduction of seminal vesicle weights was similar after Casodex and GnRH antagonist treatment, whereas flutamide was less effective. Testicular weight and spermatogenesis (assessed by light microscopical and flow-cytometric analysis) remained unaffected by Casodex and flutamide. It is concluded, that 1. Casodex, in contrast to flutamide, is a peripherally selective antiandrogen, and 2. Casodex influences release of gonadotropins into circulation less than flutamide. Therefore this antiandrogen might be useful clinically for selectively blocking androgen actions in the accessory sex glands.
Dehydration, but not vasopressin infusion, enhances the adrenocortical responses of sheep to corticotropin-releasing hormone or restraint
Authors: Matthews S. G. , Parrott R. F. 
Published: June 2009

Abstract.
Two experiments were carried out using adult castrated sheep prepared with jugular vein catheters. In Experiment 1, sheep (N=8) were injected iv with saline vehicle, vehicle + 15 or 30 μg oCRH, or subjected to 120 min mild physical stress (restraint), following a 48 h period during which water was freely available or withheld. Blood samples were taken for 30 min before and 120 min after oCRH injection, and before and during restraint, and the plasma analysed for AVP and cortisol content. Levels of AVP increased by over 500% after dehydration, but were unaffected by oCRH or restraint. In contrast, plasma cortisol was unchanged after dehydration, but increased after oCRH and restraint. Moreover, these cortisol responses were significantly greater when the sheep were dehydrated. In Experiment 2, euhydrated sheep (N =6) were infused iv with saline vehicle or vehicle + AVP for a 5-h pretreatment period, followed by a 2-h experimental period in which the animals were injected with 15 μg oCRH or subjected to 120 min restraint, as in Experiment 1. Blood samples were taken throughout the experiment from a contralateral catheter and the plasma analysed for AVP and cortisol content. The AVP infusion produced plasma levels of the hormone approximately twice those seen after 48 h dehydration in Experiment 1, but did not affect cortisol secretion. Furthermore, the cortisol response to oCRH, or restraint, was not enhanced by the AVP infusion. These results suggest that pituitary responsiveness to exogenous or endogenous CRH (restraint stress) may be enhanced in sheep by dehydration through a mechanism that does not involve an adrenal or pituitary action of circulating AVP.
The gonadotropin-releasing hormone agonist leuprolide affects the thymus and other non-reproductive systems of female rats
Authors: Blacker Charla M. , Ataya Khalid M. , Savoy-Moore Ruth T. , Subramanian Marappa G. , Mutchnick Milton G. , Dunbar Joseph C. 
Published: June 2009

Abstract.
To evaluate the effects of a gonadotropin-releasing hormone agonist on non-reproductive systems, we administered [D-Leu 6, Des-gly 10]-GnRH ethylamide (leuprolide; 5 μg/day) for 21 days to female Sprague-Dawley rats. In Experiment 1, continuous infusion (Alzet minipumps sc) was compared to injection. Increased thymus and body weights and decreased estradiol and uterine weights were noted for both administration methods. Spleen weight increased only in rats treated by continuous infusion. Ovary, kidney and liver weights did not change. Only leuprolide-injected rats had elevated LH with decreased corticosterone and ACTH levels, possibly related to the injection process. Glucose, insulin, progesterone, FSH and corticosterone/ACTH were not different. In Experiment 2, intact and ovariectomized rats were implanted with minipumps delivering leuprolide or 0.9% NaCl. Body and thymus weights increased, whereas uterine weight and estradiol declined in both leuprolide-treated and ovariectomized rats. No synergism between leuprolide and ovariectomy was noted. Thymosin α1, but not thymosin β4, increased in leuprolide-treated ovariectomized rats. Peripheral white blood cell count was elevated in leuprolide-treated intact rats and ovariectomized rats. In bone marrow, non-nucleated cell count declined in leuprolide-treated intact rats, contributing to the decreased total cell count in this group. Nucleated cell count was unaffected. Therefore, thymus weight gain was accompanied only in some cases by functional changes. Our results demonstrate that leuprolide affects non-reproductive systems, in a similar manner to ovariectomy. We suggest that such alterations may be due to the hypoestrogenic environment produced by leuprolide.
Renotropic and gonadotropic activity in homologous and heterologous hybrids of ovine luteinizing hormone and human chorionic gonadotropin subunits
Authors: Nomura Kaoru , Nakamura Yasunori , Ujihara Makoto , Ohmura Kazutaka , Toraya Shohzou , Horiba Nobuo , Demura Hiroshi 
Published: June 2009

Abstract.
We previously demonstrated the renotropic activity of ovine and porcine LH, i.e. the stimulation of [3H]thymidine incorporation into the renal DNA of castrated hypophysectomized rats. We conducted this study to determine which condition is required to promote renotropic activity. We prepared homologous (oLHα· oLHβ, hCGα·hCGβ) and heterologous (oLHα·hCGβ, hCGα·oLHβ) hybrids from isolated oLH- and/or hCG-derived subunits. Native oLH and all hybrids showed gonadotropic activity when examined for cyclic AMP generation in cultured Leydig tumour cells (MA-10). Native oLH and the hybrids which showed renotropic activity were all found to contain at least one of the oLH subunits. Our findings point out the important, special role of oLH subunits in promoting renotropic activity. The condition required is suggested to be presence of a common structure in the two oLH subunits. Such a structure should consequently not be present in hCG. A carbohydrate moiety of oLH containing a sulphate group is proposed as a candidate, but the assumption remains to be demonstrated.
Evidence for direct non-genomic effects of triiodothyronine on bone rudiments in rats: Stimulation of the inositol phosphate second messenger system
Authors: Lakatos Peter , Stern Paula H. 
Published: June 2009

Abstract.
Thyroid hormones increase cytosolic free calcium by binding to plasma membrane receptors in several tissues. This calcium increase appears to initiate extranuclear effects in these tissues. Increases in cytosolic calcium are often a consequence of stimulation of inositol phosphate second messenger pathway. Several calcemic hormones act via this signal transduction route. Therefore we investigated the effects of the metabolically active T3 and the inactive analogues 3,5-diiodotyrosine and rT3 on the inositol phosphate pathway in fetal rat limb bone cultures prelabeled with [3H]myoinositol. Labelled inositol and inositol phosphates were separated by HPLC. There was a significant increase in the radioactivity in inositol bis- and trisphosphates after 1 min of exposure to 10−7 mol/l T3. Stimulation was also observed at 10−6 mol/l T3, but not at 10−5 mol/l. Time course studies demonstrated a rapid effect of T3 on inositol phosphates within 30 seconds that lasted through 5 min. After 20 min incubation with T3, no increase was observed in inositol mono- and bisphosphates, and a decrease was seen in inositol trisphosphate. Pretreatment with indomethacin prevented these effects of T3. 3,5-diiodothyrosine and rT3 did not affect inositol phosphate metabolism. These results suggest the existence of plasma membrane-associated receptors for T3 in bone, in addition to the nuclear receptors demonstrated previously. The role of these receptors in the effects of thyroid hormones on bone remains to be established.
Increased serum concentrations of type I procollagen C-terminal propeptide and osteocalcin during a short course of calcitriol administration to adult male volunteers
Authors: Gram Jeppe , Bollerslev Jens , Nielsen Henning K. , Junker Peter 
Published: June 2009

Abstract.
To investigate bone collagen metabolism during vitamin D treatment, 15 healthy males (aged 28-45 years, median 34) were treated orally with calcitriol, 2 μg daily for 7 days and followed for a total of 2 weeks. The serum concentration of calcitriol rose markedly (median difference and 95% confidence limits: 49% (5-82), p<0.005) during treatment, whereas serum levels of calcidiol, and calcium remained unchanged. The serum level of procollagen type I C-terminal propeptide rose 15% (7-33, p<0.003), whereas no alterations were observed concerning serum procollagen type III N-terminal propeptide, and serum hyaluronan. The serum concentration of osteocalcin rose concomitantly (26% (12-45), p<0.003). All values returned to baseline levels within seven days after the treatment week. The serum levels of osteocalcin and procollagen type I C-terminal propeptide were positively correlated (rs=0.71, p<0.004) during the study. Serum procollagen type I C-terminal propeptide and serum osteocalcin did not correlate with serum procollagen type III N-terminal propeptide or serum hyaluronan either at baseline or after treatment. It is concluded that a short course of calcitriol administration to healthy males stimulates the biosynthesis of bone-related matrix proteins. By contrast, connective tissue components of predominantly extraosseous origin are not affected.
LH pulsatility and in vitro bioactivity in women with anorexia nervosa-related hypothalamic amenorrhea
Authors: Allouche Jacques , Bennet Antoine , Barbe Pierre , Plantavid Monique , Caron Philippe , Louvet Jean-Pierre 
Published: June 2009

Abstract.
LH nocturnal pulsatility and bioactivity to immunoreactivity (B/I) ratio were determined in 16 patients with anorexia nervosa-related hypothalamic amenorrhea and low sex steroid levels, and in 12 normal women in the midfollicular phase. The patients were subdivided into 2 groups: IA (N=7) without, and IB (N=9) with documented recent weight gain. Blood samples were taken from each subject at 10-min intervals from 00.00 to 06.00 h. Immunoreactive LH data were analysed with cluster analysis algorithm. A pool of aliquots from all the samples was used to evaluate bioactive LH, immunoreactive LH and LH B/I ratio in each subject. LH pulse frequency was lower in Group IA than in controls, whereas it did not differ significantly between Group IB and controls. LH pulse amplitude was lower in Group IA, and higher in Group IB than in controls. LH B/I ratio was below the control range in 3/16 patients. In conclusion, persistent hypothalamic amenorrhea does not require a permanent inhibition of the GnRH pulse generator; transient inhibition of pulsatility and qualitative abnormalities of gonadotropins could be involved in the mechanism, at least in some patients.
Basal prolactin and total lactogenic hormone levels by microbioassay and immunoassay in normal human sera
Authors: Maddox Paul R. , Jones Derek L. , Mansel Robert E. 
Published: June 2009

Abstract.
The availability of an improved microbioassay for prolactin measurement has enabled comparison of lactogenic hormone bioactivity and immunoactivity in normal human serum. Serum was studied from 61 normal females and 15 normal males. The correlation of both assays was very close for all subjects with a mean ratio of bioassay to immunoassay of 1.5 (range 0.8-2.0) for prolactin and 1.4 (range 0.5-1.9) for total lactogenic hormone. There was no significant variation in prolactin or total lactogenic hormone values by microbioassay or immunoassay with sexual or menstrual status. Postmenopausal prolactin levels were lower by both assays compared with premenopausal values with a relative and absolute decrease in prolactin bioactivity with age. These findings indicate that there is a good correlation between prolactin bioactivity and immunoactivity in human serum.
Dynamics of the acute effects of octreotide, bromocriptine and both drugs in combination on growth hormone secretion in acromegaly
Authors: Wagenaar Annie H. , Harris Alan G. , van der Lely Aart J. , Lamberts Steven W. J. 
Published: June 2009

Abstract.
The separate and combined GH-lowering effects of single doses of octreotide and bromocriptine were assessed in 51 acromegalic patients on 4 occasions each 2 days apart. Patients received sequentially: placebo sc (N=51), 50 μg octreotide sc (N=51), 2.5 mg bromocriptine po (N=40) or a combination of both drugs (N=25). With octreotide, in 28 patients (55%) GH levels were suppressed to less than 5 μg/l and 39 of them (76.5%) had a 50% or greater decrease of their basal GH level from 2 to 6 h. During bromocriptine, GH values were suppressed to below 5 μg/l in 11 patients (27.5%) and reduced by 50% or more in 21 (52.5%). The combination of both drugs acutely suppressed GH levels to less than 2 μg/l in 32%, to less than 5 μg/l in 56%, and by more than 50% in 84% of patients. Octreotide produced a stronger and faster suppression of GH levels than bromocriptine in most patients. The combination of both drugs had an additive effect on the lowering of GH levels, especially between 7 and 10 h after drug administration. These results suggest that chronic therapy with a combination of both drugs may be as effective as therapy with higher doses of either compound alone. Albeit transient, octreotide caused a rapid near total suppression of insulin release in the morning, 15 to 45 min after administration. Postprandial glucose rise, between 2 and 3.5 h after breakfast was significantly higher during octreotide than on the control day.