bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced testosterone secretion in adult rams after establishment of a high-frequency, low-amplitude pattern of LH pulses in the nonbreeding season occurs without changes in the number or binding affinity of testicular LH receptors
Authors: Sanford Lee M. , Baker Susan J. 
Published: December 2008

Abstract
When the LH signal in the ram is changed from one of large and infrequent pulses to one of small and frequent pulses, the testes quickly become more responsive to LH and testosterone secretion is elevated, perhaps because the number and (or) binding affinity of testicular LH receptors have increased. An experiment was undertaken in the nonbreeding season (July) with 10 adult Dorset × Leicester × Suffolk rams that were about 3.5 years of age and 69 ± 2 kg in body weight. Rams were given injections into the jugular vein of either 5 μg NIH-LH-S24 (in 1 ml saline) or vehicle every 80 min for 6 days. LH treament produced a series of LH pulses that occurred three times more frequently and were 70% less in amplitude than pulses in the control rams, without causing mean LH concentration to increase. Endogenously produced LH pulses were not evident in the treated rams after LH injection began. The modified LH-pulse pattern elevated mean testosterone concentration by 150% (assessed on days 2 and 5), and caused the cumulative testosterone response to LH pulses, estimated by multiplying testosterone-pulse amplitude by frequency per 6 h, to increase progressively by 180% (days −2 through 5). Enhanced testicular steroidogenic activity, presumably due to greater enzymatic activity and cholesterol availability within Leydig cells, was not associated with increases in either the concentration or affinity of LH-binding sites in the testis (assessed on days 3 and 6).
Serum testosterone levels in women with Cushing's disease
Authors: Halpin David M. G. , Burrin Jacky M. , Joplin Graham F. 
Published: December 2008

Abstract
Serum testosterone was measured pre- and post-operatively in 31 women who obtained remission of Cushing's disease following treatment by interstitial irradiation of the pituitary gland. The mean serum testosterone was initially elevated at 3.35 nmol/l, with values ranging from 0.7 to 14.4 nmol/l. Following treatment the mean serum testosterone fell to 1.42 nmol/l (i.e. normal) and all but one of the 15 patients with initially elevated pre-treatment values obtained normal levels. The pre-treatment testoterone concentrations correlated significantly (r = 0.47; p = 0.019) with the midnight ACTH concentration. The likely determinant of the raised serum testoterone would appear to be the intensity of the ACTH drive, although an individual's inherent sensitivity to ACTH may also be a factor.
Episodic nyctohemeral secretion of melatonin in adult humans: Lack of relation with LH pulsatile pattern
Authors: de Leiva Alberto , Tortosa Federico , Peinado Miguel A. , Serrano José , Rodriguez-Espinosa José , Puig-Domingo Manuel 
Published: December 2008

Abstract
The concentration of melatonin and LH were determined in plasma samples obtained at 10-min intervals during 4 h of darkness (00.00-04.00 h) from 4 normal women, age 23-27 years, in the early follicular phase of the menstrual cycle and in 6 normal men, age 23-31 years. Additionally, melatonin concentration was determined in samples obtained from the men at 10-min intervals for 4 h during the day (10.00-14.00 h). A pulsatile pattern of melatonin secretion was found for all the subjects during darkness. There was no significant difference between women and men as to the number of pulses (2.8 ± 0.5 vs 5.2 ± 1.0 per 4 h), amplitude of pulses (51.3 ± 28 vs 27.2 ± 6 ng/l), concentration per 4 h (32.5 ± 13 vs 31.0 ± 5 ng/l), or apparent half-life of melatonin (19.3 ± 2.3 vs 15.3 ± 7.5 min). The mean amplitude of the melatonin pulse correlated (r = 0.863, p<0.001) with the mean melatonin concentration per 4 h. A pulsatile LH secretion pattern was found for the 10 subjects and did not correlate significantly with the melatonin secretion pattern. The results are consistent with an independent signal for the demonstrated nyctohemeral pulsatile melatonin and LH secretions.
The relationship between some beta-adrenergic mediated responses and plasma concentrations of adrenaline and cyclic AMP in man
Authors: Philipsen E. K. , Myhre J. , Larsen S. , Nielsen M. Damkjær , Holst J. J. , Hilsted J. 
Published: December 2008

Abstract
To test the hypothesis that increments in plasma cyclic AMP during beta-adrenergic stimulation reflect integrated second messenger function of the tissues activated by the angonist, graded adrenaline infusion resulting in plasma adrenaline concentrations within the physiological range was performed in 8 healthy subjects with and without concomitant beta-adrenoceptor blockade by iv propranolol. A significant correlation was found between increments in plasma adrenaline and plasma cyclic AMP in the experiments without beta-blockade; during concomitant beta-blockade the increase in plasma cyclic AMP concentrations at low adrenaline infusion rates was prevented, whereas a small increase in cyclic AMP was found at high adrenaline infusion rates, probably owing to incomplete beta-receptor blockade. Likewise, the adrenaline-induced increments in blood substrates (glucose, lactate, glycerol and betahydroxy butyric acid) were significantly reduced but not completely prevented by beta-blockade. We conclude that an altered relationship between beta-agonist concentrations and plasma cyclic AMP may provide evidence for the existence of differences in beta-adrenergic sensitivity in man.
Long-term culture of rat mammotrope and somatotrope subpopulations separated on continuous Percoll density gradients: Effects of dopamine, TRH, GHRH and somatostatin
Authors: Hofland Leo J. , van Koetsveld Peter M. , Verleun Theo M. , Lamberts Steven W. J. 
Published: December 2008

Abstract
Normal adult female rat mammotrope and somatotrope subpopulations were separated on continuous Percoll density gradients according to differences in their density. Viable cells were recovered in 16 fractions. The cells from each fraction were cultured during 7 days after which period 4-h incubations were performed. rPRL secretion per cell increased towards the higher density fractions. No major difference in TRH, dopamine and somatostatin responsiveness was observed between mammotropes that were recovered in the different gradient fractions. In addition, no differences in somatostatin responsiveness between the somatotrope cells in the different gradient fractions were observed. However, somatotropes that were recovered in the highest density region of the gradient appeared to be more responsive to GHRH than the lower density somatotropes. In the various gradient fractions there were no paradoxical effects of TRH and dopamine on rGH release and of GHRH on rPRL release. Conclusions: 1. In long-term cultures there is no evidence for functionally different subpopulations of mammotropes and somatotropes, separated according to differences in their density, with regard to dopamine and TRH responsiveness and with regard to somatostatin responsiveness, respectively. 2. There is no evidence for a (mammosomatotrope?) subpopulation of cells showing paradoxical responses of PRL or GH release to GHRH and dopamine or TRH, respectively.
Pituitary repetitive stimulation with GnRH/TRH in women treated with three different oral steroid contraceptives
Authors: Pérez-López Faustino R. 
Published: December 2008

Abstract
Twelve untreated cycling women and 45 women using oral contraceptives were challenged iv with 50 μg of GnRH and 100 μg of TRH at 0, 90 and 180 min. The LH responses after the second and third pulses of GnRH/TRH were diminished in women treated with 30 μg of ethinylestradiol and levonorgestrel as compared with the control group, whereas the responses were severely blunted after each dose of GnRH/TRH in women treated with 50 μg of ethinylestradiol and levonorgestrel or lynestrenol as compared with both the control group and the women treated with 30 μg of ethinylestradiol and levonorgestrel. The FSH responses to GnRH/TRH in women treated with 30 μg of ethinylestradiol and levonorgestrel were similar to those in the control group, whereas there were reductions in the responses obtained in women treated with 50 μg of ehinylestradiol and progestin as compared with both the control group and the women under 30 μg of ethinylestradiol and levonorgestrel. In women treated with 30 μg of ethinylestradiol and levonorgestrel, the PRL peaks after the second and third pulses were higher than the first, and higher than the values obtained in the remaining three groups.
Tissue-specific differences in the compartmentalization of rat nuclear triiodothyronine receptors
Authors: Barsano Charles P. , Iqbal Zafar , Pullen Gordon L. , Muñoz B. Elena , Singh Sant P. 
Published: December 2008

Abstract
In addition to the recognized rat liver nuclear T3 receptor extractable with hypertonic salt, recent studies have described nucleoplasmic receptors extractable with isotonic KCl and salt-resistant receptors localized to the nuclear matrix. A method was developed for the determination of intra-nuclear receptor distribution 1in small samples of nuclei dispersed within glass wool matrices. After in vitro labelling with 6 nmol/l [125I]T3, dispersed nuclei were sequentially extracted with 0.15 mol/l KCl (yielding nucleoplasmic receptors), 0.4 mol/l KCl, and 2 mol/l KCl (the latter two concentrations yelding hypertonic salt-extractable receptors). The salt-resistant receptors were retained within the glass wool columns. The intra-nuclear distribution of in vivo labelled receptors was very similar to that obtained by in vitro labelling. The equilibrium association constants for L-T3 binding among the receptor pools ranged from 0.6 × 109 to 1.0 × 109 l/mol. The distribution of total nuclear receptors within each nuclear compartment was (percentage of nucleoplasmic, hypertonic salt-extractable, and salt-resistant receptors): Cerebrum: 23.6, 52.2, 24.2; Liver: 25.2, 57.2, 17.5; Kidney: 45.9, 33.5, 20.6; Testis: 65.5, 14.7, 19.7; and Spleen: 66.7, 18.7, 14.6. The rank order of percentage of hypertonic salt-extractable receptors approximates the rank order of thyroid hormone-responsiveness by traditional criteria. The inverse is true for the percentage of nucleoplasmic receptors. The percentage of salt-resistant receptors was very similar in all of the tissues.
Effects of a dopamine antagonist (metoclopramide) on the release of LH, FSH, TSH and PRL in normal women throughout the menstrual cycle
Authors: Seki Katsuyoshi , Nagata Ichiro 
Published: December 2008

Abstract
To obtain further insight into the role of endogenous dopamine on the adenohypophyseal hormones secretion in normal women, responses of the adenohypophyseal hormones to a dopamine antagonist, metoclopramide, were evaluated in 7 normal women during the early follicular, late follicular and mid-luteal phases of the menstrual cycle. PRL increments following metoclopramide were similar in all phases. During the early and late follicular phases, metoclopramide induced no significant change in circulating LH levels. However, a significant rise in serum LH was observed following metoclopramide during the mid-luteal phase. No significant changes in serum FSH levels were observed after metoclopramide during any of the 3 phases of the cycle. Following metolopramide, serum TSH levels significantly rose in all phases. TSH increments following metoclopramide were significantly lower in the mid-luteal phase than in the early follicular phase. These results suggest that the modulatory effect of endogenous dopamine on adenohypophyseal hormones secretion is variable and selective throughout the normal menstrual cycle.
Development of a sensitive enzyme immunoassay for LH determination in bovine plasma using the streptavidin-biotin technique
Authors: Mutayoba B. M. , Meyer H. H. D. , Schams D. , Schallenberger E. 
Published: December 2008

Abstract
Using the biotin-streptavidin amplification technique, highly sensitive specific second-antibody enzyme immunoassays for determining LH in bovine plasma with long (48 h) and short (4 h) incubation periods were developed. Biotin was linked to bLH by the N-hydroxysuccimidine method and the product (biotinyl-bLH) used to bridge between streptavidin-peroxidase and the immobilised bLH antibody in competitive tests. The assays were validated and their performance compaired with a radioimmunoassay currently in use. The sensitivities of the long and short incubation enzyme immunoassays (8 pg and 15 pg/well, respectively) were superior to that of 5-day incubation radioimmunoassay (100 pg/tube). Plasma interference in both assays were acceptable and volumes of 5 to 40 μl gave parallel standard curves and comparable LH levels, 10–20 μl plasma was sufficient to measure LH baseline levels by the long incubation enzyme immunoassay. The mean recovery of added standard bLH to plasma samples containing different endogenous LH was >90% (range 91.7–112) in both assays. The intra- and inter-assay variations of both assays were less than 10 and 17%, respectively. When both enzyme immunoassay and radioimmunoassay were used to measure LH in cyclic cows, the basal levels measured by enzyme immunoassay were lower than that measured by radioimmunoassay. Enzyme immunoassay offers an attractive alternative to the lengthy radioimmunoassay in current usage, with an added advantage of employing non-isotopic label.
Peripheral blood T cell activation after radioiodine treatment for Graves' disease
Authors: Teng Wei-Ping , Stark Roger , Munro AlistairJ. , Young Stuart McHardy , Borysiewicz Leszeck K. , Weetman Anthony P. 
Published: December 2008

Abstract
Radioiodine therapy for Graves' thyrotoxicosis produces a rise in thyroid autoantibodies in the first three months after treatment, but little is known of its effects on T cells. We have therefore followed the changes in T cell subsets in sequential samples from 23 patients with Graves' disease treated with radioiodine, using dualcolour flow cytometry. In the first month after treatment there was a significant rise in activated T cells, identified by the markers HLA-DR (la) and CDw26/Tal (p<0.025 in both cases). CD45RO-positive T cells, which are the primed population containing memory cells, also increased (p<0.025), but there was no change in CD45R-positive, resting T cells or in the CD4 to CD8 (helper to cytotoxic/suppressor) ration. Vicia villosa-binding T cells, containing the contrasuppressor population, showed a more variable response, but the trend was to an overall increase from pre-treatment values (p<0.025). The changes did not appear to be related to antithyroid drug treatment, since they were seen irrespective of whether patients continued such therapy. These results suggest that T cell activation and enhanced contrasuppressor activity may in part be responsible for the rise in autoantibodies after radioiodine. The T cell changes could also contribute to the worsening of ophthalmopathy seen in some radioiodine-treated patients.
Postpartum thyroid dysfunction in Bangkok: A geographical variation in the prevalence
Authors: Rajatanavin Rajata , Chailurkit La-or , Tirarungsikul Kanokporn , Chalayondeja Wirawat , Jittivanich Uraiwan , Puapradit Winit 
Published: December 2008

Abstract
To determine the prevalence of thyroid dysfunction in Thai postpartum women, we evaluated thyroid function and thyroid autoantibodies in 812 consecutive unselected women at 1.5 months post partum. At 3.5 months post partum 570 women without previous thyroid abnormality returned for a second set of thyroid function test. The prevalence of thyroid dysfunction was 1.1%, which was less than that reported from other countries. Various types of postpartum thyroid dysfunction, namely, transient thyrotoxicosis followed by transient hypothyroidism, transient thyrotoxicosis or hypothyroidism occurring alone or permanent hypothyroidism were encountered. Eight out of 9 patients with thyroid dysfunction had thyroid autoantibodies. Fine needle aspiration biopsy of the thyroid was done in 4 patients and all showed lymphocytic thyroiditis. Even though Bangkok is an iodine surfeit area, iodine intake is relatively lower than in other areas where the prevalence of postpartum thyroid dysfunction is much higher. The discrepancy in geographic prevalence of postpartum thyroid dysfunction may result from the interaction of immunogenetic heterogeneity of different ethnic background, environmental iodine intake, and other unidentified environmental factors.
Hypoglycemia owing to inappropriate glucagon secretion treated with a continuous subcutaneous glucagon infusion system
Authors: Abs Roger , Verbist Louis , Moeremans Marleen , Blockx Pierre , De Leeuw Ivo , Bekaert Jozef 
Published: December 2008

Abstract
A selective glucagon deficiency was documented in a 36-year-old female patient suffering from severe hypoglycemic attacks. The extremely low fasting plasma glucagon levels could not be stimulated by hypoglycemia. The increase in plasma glucagon during stimulation with arginine did not prevent hypoglycemia provoked by the simultaneous insulin secretion. Treatment consisting of a continuous sc glucagon infusion system resulted in correction of both postabsorptive and postprandial hypoglycemia. Further lowering of the glucose level during an arginine test could be the hallmark of this hypoglycemic syndrome characterized by an inappropriate glucagon secretion. This case report would indicate that epinephrine cannot prevent hypoglycemia when glucagon release is completely deficient.
The effect of orchidectomy on rat pituitary responsiveness to GHRH depends on age
Authors: Pinilla L. , López F. J. , Aguilar E. 
Published: December 2008

Abstract
Pituitary responsiveness to GHRH (1-29) NH2 (GHRH, 5 μg/kg iv) was analysed under sodium pentobarbital anesthesia (50 mg/kg ip), on days 30 and 90 in male rats orchidectomized or sham-operated 7 days earlier. Other groups of rats were orchidectomized or shamoperated on day 23 and tested on days 30, 45, 60 and 90. In the sham-operated animals, GHRH stimulated GH secretion on day 90, but not on day 30. GHRH-induced secretion was similar on days 45, 60 and 90 in orchidectomized and sham-operated animals. Orchidectomy on day 83 reduced this GHRH-induced GH secretion on day 90. In contrast, orchidectomy on day 23 enhanced the pituitary responsiveness to GHRH a week later. These results suggest that the increase in pituitary responsiveness to GHRH with age is independent of the testicular function and that the effect of orchidectomy depends on both the age of the rats at orchidectomy and the time elapsed between the orchidectomy and the administration of GHRH.
Histamine-induced paradoxical GH response to TRH/GnRH in men and women: Dependence on gonadal steroid hormones
Authors: Knigge Ulrich , Thuesen Benedikte , Dejgaard Anders , Svenstrup Birgit , Bennett Paul 
Published: December 2008

Abstract
A stimulatory GH response to TRH and GnRH occurs frequently in patients with various pathological conditions, but is absent in normal subjects. We have previously shown that histamine induced a paradoxical GH response to TRH in normal men. Since gonadal steroids influence GH secretion, we investigated whether infusion of histamine might induce a GH response to combined administration of TRH (200 μg) and GnRH (100 μg) in 6 normal women during the early follicular and luteal phase of the same menstrual cycle and in 7 normal men. Histamine had no effect on basal GH secretion in men or in women during the two phases of the menstrual cycle. However, compared with saline, histamine induced a GH response to TRH/GnRH in men (GH peak: 5.5 ± 1.0 vs 1.4 ± 0.3 μg/l; p<0.01) and in women during the luteal phase (GH peak: 5.2 ± 1.6 vs 1.5 ± 0.4 μg/l; p<0.025), but not during the early follicular phase of the cycle (GH peak: 1.7 ± 0.5 vs 1.6 ± 0.3 μg/l). In luteal-phase women the GH response to TRH/GnRH correlated with the serum estradiol-17β level (GH area/E2: r=0.98; p<0.005) and the serum estrone level (GH area/E1: r=0.81; p<0.05). In men the GH response to TRH/GnRH did not correlate with estrogen or androgen levels. We conclude that high physiological levels of estrogens are pertinent to the activation of a histamine-induced GH response to TRH/GnRH in women, whereas the role of androgens and estrogens for the induction of the response in men seems more complex. Furthermore, the study indicates that histamine may increase the sensitivity of GH release to nonspecific stimuli.
Kidney tissue insulin-like growth factor I and initial renal growth in diabetic rats: Relation to severity of diabetes
Authors: Flyvbjerg Allan , Ørskov Hans 
Published: December 2008

Abstract
The initial renal hypertrophy in experimental diabetes is dependent on the prevailing blood glucose level and is associated with renal accumulation of insulinlike growth factor I. To investigate the relationship of blood glucose to kidney IGF-I, a graded range of diabetic aberration was established in young rats by iv injection of increasing amounts of streptozotocin (25–80 mg/kg) at day 0. In 30 diabetic rats the mean of day 1 and day 2 blood glucose concentrations ranged from 6.2 to 32.0 mmol/l and 24-h urinary glucose excretion (24–48 h) from 0.04 to 43.3 mmol/24 h. The right kidneys were removed after 48 h, weighed and their IGF-I concentration analysed by radioimmunoassay. Kidney IGF-I was positively correlated to blood glucose (r = 0.66, p<0.0001) as well as to 24-h urinary glucose output (r = 0.54, p<0.005). At this early stage, kidney weight already correlated to blood glucose (r = 0.60, p<0.0005). No relationship between kidney IGF-I and kidney weight was found. However, if animals with severe diabetes were excluded, a significant correlation could be established (r = 0.51, p = 0.01, N = 24). The results support the hypothesis that IGF-I plays a causal role in the initial renal hypertrophy of experimental diabetes.
Relaxin and prostaglandin on oxytocin secretion from bovine luteal cells during different stages of gestation
Authors: Musah Al-Hassan I. , Schwabe Christian , Anderson Lloyd L. 
Published: December 2008

Abstract
The objective of this study was to determine whether bovine luteal cells from different stages of gestation secrete oxytocin and whether relaxin, cloprostenol (a potent analogue of prostaglandin F2α), estradiol-17β, and LH can acutely alter oxytocin secretion. Bovine luteal cells (105) were cultured for 24 h without treatment and with medium-hormone replacement every 24 h. Oxytocin was quantified by radioimmunoassay of the culture media. Basal oxytocin secretion was similar (22-31 pmol/l, p>0.05) for all stages of gestation (days 100, 145, 160, 185, 200, 210, and 240). Relaxin induced a dose-dependent suppression of oxytocin release. After 24 h of incubation, addition of 0, 16.7, 83.5, and 167 nmol/l porcine relaxin (3000 U/mg) induced 54 ± 4, 105 ± 16, 47 ± 4, and 38 ± 4 pmol/l of oxytocin in cells from 160-day-old corpora lutea and 138 ± 12, 21 ± 2, 19 ± 3, and 15 ± 2 pmol/l oxytocin in cells from 240-day-old corpora lutea. From luteal cells of 160- and 240-day-old corpora lutea, 2 μmol/l cloprostenol induced a marked increase (p<0.01) of 208 ± 39 and 371 ± 34 pmol/l oxytocin, respectively. Addition of 167 nmol/l relaxin did not prevent cloprostenol-induced oxytocin secretion during the first 48 h, but a decrease (p<0.05) in oxytocin occurred in day 3 cell cultures. These results indicate that cultured luteal cells obtained from different stages of gestation in cattle can secrete oxytocin and suggest a role for relaxin in the regulation of oxytocin release.