bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient impairment or delay of urinary trihydroxypregnanone (THS) response to metyrapone in boys with delayed adolescence and in patients with isolated growth hormone deficiency
Authors: Zachmann M. , Tassinari D. , Sorgo W. , Exner G. U. , Kempken B. , Prader A. 
Published: December 2008

Abstract.
Twentythree boys with delayed adolescence (age 15.7 ± 2.0, bone age 12.4 ± 2.1 years) were studied. Their cortisol response to insulin was normal. After oral metyrapone (500 mg/m2 by mouth) one to three consecutive 12 h urine samples were collected for analysis of THS. Thirtyseven tests with 37 first, 21 second, and 11 third samples were carried out. The results could be divided into two main groups: 25 tests (group A) were subnormal in the first sample, 12 of them with a very weak (40 ± 8 μg/m2/12 h) and 13 with an insufficient (191 ± 16 μg/m2/12 h) THS response. Values in the second and third sample were higher, indicating a dealyed response. In 12 tests (group B), the results were normal (1016 ± 143 μg/m2/12 h) in the first and lower in the second and third samples. In three patients with repeated tests, there was improvement with increasing bone age.
The THS-responses to metyrapone did not correlate with those of growth hormone, gonadotrophins, and TSH to stimuli. It is concluded that the THS-response to a single dose of metyrapone may be temporarily insufficient or delayed in delayed adolescence. We interpret this finding as showing transiently reduced or slow hypothalamic responsiveness.
Kinetics of LRH-induced LH-release in vivo: influence of LRH pre-treatment
Authors: Koiter T. R. , Pols-Valkhof N. , Schuiling G. A. 
Published: December 2008

Abstract.
The influence of an LRH injection (50 ng/ 100 g b.w.) on the LH-response to a second, equally large LRH injection or a constant rate infusion of LRH (104 ng/h), administered 1 h later, was studied in phenobarbitone-anaesthetized, oil- or oestradiol benzoate (OeB)-treated rats ovariectomized (OVX) 5 weeks earlier. From the plasma LH concentration the mean maximal LH secretion rates, as well as the amounts of LH secreted, were calculated on the basis of a one-compartment model, proceeding from a half-life of LH of 15 min.
In both the oil- and the OeB-treated animals, not only the mean maximal LH secretion rate, but also the amount of LH secreted during the first hour following the injection, was significantly higher after the second LRH injection than after the first one (LRH self-priming effect). Infusion of LRH in LRH-primed OVX rats revealed that the LH secretion accelerates immediately after the start of the infusion and this acceleration lasts about 1 h. In the saline-injected controls, on the other hand, the LH secretion, although elevated, remains constant during the first 30 min of LRH infusion and accelerates only thereafter during about 1 h. Yet, maximal LH secretion rates are not statistically different between the LRH-primed oil- or OeB-treated OVX rats and their respective saline-injected controls.
It is concluded that the self-priming effect of LRH does not lead to an increase of the ultimate maximal LH secretion rate. Rather, during priming the conditions necessary for immediate acceleration of the LH secretion rate are established, and priming thus causes a shift in time, that is, an advancement, of the LH-response to a subsequent LRH stimulus.
TSH and TSH-subunit production by human thyrotrophic tumour cells in monolayer culture
Authors: Filetti S. , Rapoport B. , Aron D. C. , Greenspan F. C. , Wilson C. B. , Fraser W. 
Published: December 2008

Abstract.
Studies were performed on pituitary adenoma tissue obtained from a patient with hyperthyroidism secondary to inappropriate thyrotrophin (TSH) secretion. Cells dispersed enzymatically were established in primary monolayer culture for a period of 39 days. Intact TSH and TSH-subunit release into the culture medium declined over the initial 20 days, followed by a rebound in TSH and β-TSH production until the time of subculture at day 39. In vitro α-TSH production declined more slowly than did TSH and β-TSH, but did not recover in parallel with intact TSH. Production of α-TSH by cultured cells, at different times, was 20–80-fold greater than that of β-TSH. In the pituitary tissue α-TSH content (112 ng/mg tissue) was 8.6-fold greater than the β-TSH concentration (13 ng/mg tissue), but similar to intact TSH content (105 ng/mg tissue). In serum, the α-TSH concentration (6.5 ng/ml) was lower than in most previously reported patients with thyrotrophic adenomata. TSH bioactivity in tumour tissue (approximately 600 ng/mg tissue) was greater than the immunoreactive TSH concentration. LH, FSH and prolactin were undetectable in tumour tissue, and in the culture medium throughout the period of cell culture. Exposure of thyrotroph monolayers to 10−6 m TRH for 4 h led to 32%-– 600% increases in TRH release, depending on the day of culture and the cell flask utilized. The α-TSH response to TRH paralleled that of intact TSH, β-TSH being unmeasureable. Incubation of cell monolayers for 4 h in 5 × 10−7 m dopamine decreased TSH and α-TSH secretion into the medium. In contrast, exposure of cells to T3 at concentrations as high as 10−6 m did not affect TSH secretion. Surprisingly, TRH (10−7 m to 2 × 10−6 m) inhibited cultured thyrotroph cAMP content by about 50%; cGMP levels were unaffected.
This study, the first to examine secretory function of human thyrotrophic tumour cells in vitro, confirms the disproportionate production of α-TSH by these tumours, even though this may not be apparent from the level of the α-subunit in serum. The data indicate that TSH secretion by thyrotroph tumour cells, at least from this particular patient, remains sensitive to TRH stimulation and dopamine inhibition, but insensitive to inhibition by T3. Not all TSH bioactivity is reflected by the immunoassayable TSH concentration, suggesting that the tumour may be producing variants of normal TSH that nevertheless retain biological activity. Finally, the data suggest that, at least in this particular tumour, TRH stimulation of TSH secretion is not mediated by cAMP as a second messenger.
Dexamethasone suppressible hyperaldosteronism in a child with nephrosclerosis
Authors: Lee Stanley M. , Lightner Elmer , Witte Marlys , Oberfield Sharon , Levine Lenore , New Maria I. 
Published: December 2008

Abstract.
A 9 year old Mexican boy presented with severe hypertension, hypokalaemia and features suggesting acute glomerulonephritis. Nephrosclerosis was present on renal biopsy. Aldosterone levels were unresponsive to variations in dietary salt intake and plasma renin activity was suppressed. Following oral dexamethasone therapy (2 mg/day), plasma aldosterone decreased to undetectable levels, serum potassium normalized and plasma renin activity gradually increased. Dexamethasone also restored the normal responsiveness of the renin-aldosterone system to postural stimuli.
The patient exhibited a marked response to a single dose of ACTH with a rise in plasma aldosterone. Long-term blood pressure control and normal potassium levels have been achieved with oral prednisone therapy (5 mg/day) for a period of one year. This case of dexamethasone suppressible hyperaldosteronism (DSH) illustrates that the degree of hypertension in this syndrome may produce severe renal microvascular lesions. DSH should be considered in all children who present with low renin hypertension.
Rat placental hormones: attempts for identification of rat chorionic gonadotrophin and rat placental lactogen by in vivo experiments
Authors: Tabarelli Marco , Kofler R. , Schwarz S. , Wick G. 
Published: December 2008

Abstract.
Rat placental extracts (rPE) were investigated in bioassays for their possible content of rat placental lactogen (rPL) and rat chorionic gonadotrophin (rCG). Luteotrophic and lactogenic activity of rPL was assessed by substitution of rats depleted of endogenous prolactin (Prl) by means of bromoergocryptine (BEC) in early pregnancy and the period of lactation, respectively. The abortifacient effect of a single dose of BEC on day 6 of pregnancy was abolished by rPE equivalent to 1 g rat placenta corresponding to 5 IU bovine Prl (NIH-P-B 2). Substitution was necessary until the evening of day 7 indicating that rPL does not take over the function of Prl before day 8. During lactation rPE reversed the lactation inhibiting effect of daily BEC treatment. In this assay rPL activity corresponded to 1.25–2.5 IU bPrl/g placenta.
In order to test for the possible existence of rCG the gonadotrophic activity of rPE was assessed in immature female mice. No gonadotrophic activity was found when rPE equivalent to 1 g rat placenta was administered, whereas equivalents of 3 mg human placenta and 12 mg rat pituitary entailed a dose-dependent response. In this system 0.12 IU human chorionic gonadotrophin (hCG), which served as standard, was the minimal dose (MD) resulting in increased uterine weight.
In addition rPE was tested in the immature female rat, where the limit of detection was found to be 0.5 IU hCG. Again no gonadotrophic activity was found in rPE. As the effects of rCG might have been restricted to its presumed target, the corpus luteum of pregnancy, rPE was also tested in pregnant rats depleted of endogenous luteinizing hormone (LH) by a single injection of anti-LH antibodies on day 10 of pregnancy. A MDof 0.5 IU hCG, which served as standard, prevented resorption of foetuses in all animals tested. rPE equivalent to 3.5 g rat placenta, rat pregnancy serum of day 18 and placental transplants could not substitute for endogenous LH.
Pharmacokinetics of norethindrone acetate in women after the insertion of a single subdermal implant releasing norethindrone acetate
Authors: Singh Harbans , Uniyal J P , Jha P , Takker D , Murguesan K , Hingorani V , Laumas K R 
Published: December 2008

Abstract.
The metabolic clearance rate (MCR) of norethindrone acetate1 (NETA) and norethindrone (NET) levels in plasma were studied after an iv injection of [3H]NETA in three women before and at 1 week, 1, 2 and 6 months following the insertion of a single silastic subdermal implant releasing microquantities of NETA. No significant change in the MCR of NETA was observed at 1 week (459 ± 72 1/day), 1 month (489 ± 113 1/day) and 2 months (522 ± 144 1/day) compared with that of control (525 ± 108 1/day). However, MCR of NETA showed significant increase in women exposed to continuous presence of NETA for a period of 6 months (608 ± 121 1/day; P < 0.025). NETA was rapidly and extensively metabolized into NET. At 1 week, 1, 2 and 6 months of study, NET was observed to be present in higher amounts compared with NETA. The production rate (PR) of progesterone decreased significantly at 2 and 6 months of NETA implant insertion compared with the PR before the insertion of implant.
Effect of opioid peptides on gonadotrophin secretion
Authors: Motta M. , Martini L. 
Published: December 2008

Abstract.
The intraventricular injection of 25 μg of Methionine-Enkephalin (Met-Enk) induces a significant increase of serum LH levels in long-term ovariectomized rats 15, 30 and 60 min following administration. The synthetic Met-Enk agonistic analogue [D-Ala2]Methionine-Enkephalinamide ([D-Ala2]Met-Enk) also enhances significantly serum LH levels at 30 and 60 min; under the same experimental conditions neither Met-Enk nor [D-Ala2]Met-Enk modifies serum levels of FSH following intraventricular injections into ovariectomized animals. It is concluded that, under particular circumstances, opioid peptides of the Met-Enk family may stimulate LH release.
Plasma gonadotrophins profile in relation to body composition in underprivileged boys
Authors: Parra A. , Ramos-Galván R. , Cervantes C. , Sánchez M. , de la Vega M. A. Gálvez 
Published: December 2008

Abstract.
The plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were measured in 250 underprivileged boys (UP boys) aged 9.0 to 15.9 years living in a State orphanage and in 357 clinically healthy boys of the same age (with weight and height between the 3rd and 97th percentile for Mexican standards) and correlated with chronological age (CA), weight, height and calculated lean body mass (LBM) and total body fat (TBF). On a group basis, UP boys had a 2 years delay in the onset of clinical signs of puberty as well as a mild degree of malnutrition. In both groups of boys, the mean weights at time of initiation of the adolescent growth spurt in weight and at time of peak velocity of weight gain were very close to each other and similar to the values reported for Caucasian boys. The same phenomenon was true for their heights and the amounts of LBM and TBF (whether as an absolute value or as a percentage of body weight). Based on CA mean plasma FSH concentrations in UP boys were lower than normal from 11.0 to 13.9 years and the subsequent steep rise of this hormone occurred 2 years later than in healthy boys; however, when analyzed as a function of body weight, height or LMB, no such quantitative or qualitative differences emerged. On the other hand, mean plasma LH concentrations in UP boys were higher than in healthy boys only up to certain CA (< 12.9 years), weight (< 42.9 kg), height (< 147.0 cm), LBM (< 35.0 kg) or TBF (< 9.0 kg); however, no steep rise in plasma LH was observed in contrast to healthy boys. Therefore, although from a chronologic view point UP boys had a delayed onset in plasma gonadotrophins changes, they did occur in association with the attainment of similar weight, height and LBM as in healthy boys. This observation seems to support further the hypothesis of a close association between a 'critical' level of LBM (and not body fat) and the initiation of puberty, both in healthy and multiply deprived boys.
Immunochemical and biological characterization of calcitonin originating from transplanted medullary thyroid carcinoma in rats
Authors: Myhre Lisbeth , Ekeland Arne , Gautvik Kaare M. 
Published: December 2008

Abstract.
The immunoreactive and biological activities of calcitonin (CT) produced by transplanted rat medullary thyroid carcinomas (MCT) have been studied. Immunoreactive CT (iCT) in serum and in MCT tissues of rats carrying tumours of generations 5–8 was characterized by gel filtration on Sephadex G-100 followed by radioimmunological measurements using region specific antiserum. The hypocalcaemic effect of sera and tumour extracts was tested in a rat bioassay.
Rats with transplanted MCT of the 5th and 6th generations had mainly (70–84%) circulating iCT species of molecular size comparable to intact hormone. However, in rats with tumours of the 7th and 8th generations corresponding circulating iCT forms comprised less than 52% of total immunoreactivity while 32–38% eluted earlier. In conparison, iCT corresponding to intact hormone represented 30–50% of total immunoreactivity in the tumour extracts and no differences were observed between the generations.
Subcutaneous injections of sera from MCT rats and of tumour extracts reduced the serum levels of ionized calcium in test rats. The sera containing mainly intact iCT showed the strongest biological potency.
We conclude that rat MCT transplanted under the kidney capsule is able to secrete biologically active CT. However, the heterogeneity of circulating iCT increases in rats with transplanted tumours of older generations, approaching the heterogeneity of stored hormone in the gland.
Effect of GIP on the secretion of insulin and somatostatin and the accumulation of cyclic AMP in vitro in the rat
Authors: Szecówka J. , Grill V. , Sandberg E. , Efendić S. 
Published: December 2008

Abstract.
The effects of gastric inhibitory polypeptide (GIP) on insulin secretion as well as on the intra-islet accumulation of [3H]cyclic AMP were investigated in isolated pancreatic islets of the rat. In the presence of 6.7 mmol/l of glucose, 3.0 and 30 nmol/l of GIP induced both insulin and [3H]cyclic AMP responses, while lower and higher concentrations of the peptide were ineffective. A coupling of the two parameters was also found with regard to interaction between glucose and GIP. Thus while 30 nmol/l of GIP was stimulatory together with 6.7, 16.7 or 33.3 mmol/l of glucose, the peptide stimulated neither insulin release, nor the accumulation of [3H]cyclic AMP in the presence of a low concentration of glucose (3.3 mmol/l).
The concomittant release of insulin and somatostatin was studied in the perfused pancreas in order to assess a possible influence by somatostatin on the dose-response pattern for GIP-induced insulin release. In this preparation 1.0 to 10 nmol/l of GIP stimulated insulin and somatostatin secretion; however while these concentrations were equipotent on insulin release, 10 nmol/l of GIP stimulated somatostatin release more than 1 nmol/l, indicating differences in dose-reponse curves for the GIP-induced stimulation of the two hormones.
It is concluded that 1) modulation of GIP-induced insulin release is coupled to changes in cyclic AMP response in the islet, 2) GIP-induced somatostatin secretion may influence the concomittant insulin response.
Somatomedin production by rat liver in organ culture
Authors: Binoux Michel , Lassarre Claudine , Hardouin Nathalie 
Published: December 2008

Abstract.
Radioligand assays have been used to study the production of insulin-like growth factor (IGF) and its carrier (IGFCP) by rat liver in organ culture. Bound IGF released into the culture medium was dissociated and separated from its carrier by gel filtration in 1 m acetic acid. IGF was measured by a competitive protein-binding assay using human IGF and the specific IGFCP produced by rat liver. IGF CP concentrations were assessed in terms of IGFCP binding to labelled IGF, compared to a reference IGFCP preparation obtained from rat serum.
Without added hormone,the ratios IGF:total protein and IGFCP:total protein in the culture media after 3 days' culture were approximately 7 and 70 times higher, respectively, than those in serum.
GH and insulin both stimulated IGF production. The response was dose-dependent, and significant at physiological concentrations of hormone (10 ng/ml GH and 10 μU/ml insulin. With 1 μg/ml GH and 1 mU/ml insulin, the IGF concentrations in the media on average reached 2½ times the base-line level. These hormones had no significant effect on IGF CP production.
One ng/ml cortisol stimulated IGF production, but, in response to increasing concentrations, there was a dose-dependent decrease in IGF production. By contrast, IGFCP production was stimulated and there was a positive correlation between the carrier concentration in the culture media and the amount of cortisol added.
The results indicate that insulin and cortisol, in addition to GH, have a direct influence on IGF production by the liver in vitro. They also suggest that the biosyntheses of IGF and its carrier are subject to different systems of regulation.
Observations on the effects of prolactin on LH-receptors and steroidogenesis in corpus luteum and testis of the hypophysectomized rat
Authors: van Straalen R. J. C. , Zeilmaker G. H. 
Published: December 2008

Abstract.
In this study the effects of hypophysectomy and autotransplantation of the pituitary gland on the concentration of hCG-binding sites (LH-receptors) and steroidogenesis in the corpus luteum and the testis of the rat were investigated.
It was found that during pseudopregnancy both hCG-binding to homogenates of isolated corpora lutea and the progesterone levels in blood increase until day 7 and subsequently decrease until day 13. Hypophysectomy on day 5 led to a decrease of the number of LH-receptors and the serum progesterone level. By contrast hypophysectomy followed by autotransplantation of the pituitary gland increased the LH-receptor concentration and progesterone synthesis in spite of non-detectable LH-levels. Progesterone implants in hypophysectomized rats did not influence the number of LH-receptors. Hypophysectomy on day 0 without pituitary gland transplantation did not prevent the formation of some luteal LH-receptors measured on day 5 although progesterone was not secreted.
A similar effect of prolactin secreted by pituitary autografts on LH-receptors was seen in the testis. The rapid decline of the number of binding sites normally observed after hypophysectomy was prevented by the presence of two pituitary autografts. Testosterone and LH-levels were non-detectable in the operated male rats.
These data show that progesterone secretion by the corpora lutea is always associated with the presence of LH-receptors, regardless whether serum LH-levels are detectable or not. Moreover it appears that prolactin maintains or even increases the amount of LH-receptors in hypophysectomized male and female rats.
Thyroid hormone dependent nuclear proteins from rat liver
Authors: Rodriguez-Pena Angeles , Bernal Juan 
Published: December 2008

Abstract.
Two nuclear proteins from rat liver were shown to be dependent on thyroid hormones. These proteins were present in the nucleosol or nucleoplasmic fraction, and were extracted from the nuclei with 0.15 m NaCl at pH8. After thyroidectomy, a 120 000-Mr polypeptide decreased in concentration to levels below 10% of normal control rats and another polypeptide of 81 000-Mr was increased. Treatment with T4 at physiological replacement doses for several days restored the levels of both proteins to normal. A single administration of 50 μg T3 induced a detectable increase of 120K after 14 h, with maximal effects at 48 h after administration. The minimum effective dose of T3 on 120K was 0.5 μg administered for three days. Preliminary observations suggest that the response of 81K to thyroid hormones is much more sensitive than that of 120K. The physiological role of these polypeptides is unknown, but they could be involved in the mode of T3 action at the nuclear level.
Biological activity of des-asp-,des-arg-angiotensin II in man
Authors: Kono Tsuyoshi , Ikeda Fumitake , Oseko Fumimaro , Ohmori Yoshiaki , Nakano Ryuichi , Muranaka Hideo , Taniguchi Ataru , Imura Hiroo , Khosla Mahesh C. , Bumpus F. Merlin 
Published: December 2008

Abstract.
The biololgical activity of des-asp1-,des-arg2-angiotensin II (3-8AII) was studied in man. When 3-8AII was infused iv at rates of 22 and 308 pmol (17.5 and 250 ng)/kg · min separately into 5 normal men each for 120 min, blood pressure showed no change, plasma renin activity (PRA) decreased gradually and plasma aldosterone showed a gradual slight increase. The lower dose of 3-8AII partially inhibited captopril-induced PRA increase and plasma aldosterone decrease in the same 5 normal men and the higher dose of the hexapeptide completely abolished them. In one of the 5 normal men blood pressure rose in response to doses of 3-8AII greater than 2220 pmol (1750 ng)/kg · min. When 3-8AII was infused iv at 308 pmol/kg · min into 2 patients with Bartter's syndrome for 60 min, it caused marked decreases in PRA and plasma aldosterone but no change in blood pressure. This decrease in plasma aldosterone is thought to be secondary to the decrease in PRA. From these results it is evident that 3-8AII has a minimal pressor action, a weak aldosterone-stimulating action and a significant renin-suppressing action in man and this PRA-lowering action is thought to be due to direct inhibition of renin release by its whole molecule or a smaller part of the molecule.