bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissociation of the triiodothyronine receptor from the nucleus induced by cations: evidence for divalent cation sensitive and insensitive nuclear sites
Authors: Bernal Juan , Perez-Castillo Ana 
Published: December 2008

Abstract. Aliquots of purified rat liver nuclei were diluted at 0°C in isotonic buffers containing monovalent (Na+) or divalent (Ca2, Mg2+) cations. At different times following dilution the nuclear suspensions were centrifuged and the T3 receptor was measured in KCl extracts of the nuclear pellets. The rate of receptor loss after dilution in EDTA was 0.0025 min−1. Dilution in the presence of cations caused a fast release of receptor during the first 10 min. This phase, which was not observed when the nuclei were diluted in EDTA without salt, was followed by a second phase where the receptor was released at the same rate as in EDTA. Receptor release was only dependent on the presence of cations in the dilution buffer during the first 10 min after dilution. The amounts of receptor remaining in the nuclei after the first 10 min of dilution were 51.8 ± 9.2%, in the presence of Ca2+and Mg2+, 38.6 ±8.9% in 0.15 m NaCl, and 18.0 ± 4.8% in 0.15 m NaCl in the presence of Ca2+ and Mg2+. The release of receptor was not influenced by the integrity of the nuclear membrane.
These results suggest the presence of divalent cation sensitive and insensitive nuclear sites for the T3 receptor, in amounts which could be estimated to be about 48 and 52%, respectively. Other interpretations are also possible, such as the presence of a high proportion of free receptors in the nucleosol, which could be released during the first phase of dilution if the negative charges in chromatin are blocked by cations to avoid redistribution of receptors immediately after dilution.
Dynamic evaluation of prolactin secretion by successive TRH and metoclopramide stimulations
Authors: Kauppila Antti , Heikkinen Jorma , Viinikka Lasse 
Published: December 2008

Abstract. We evaluated the clinical applicability of a 2-h test in which the prolactin (Prl) responses to thyrotrophin releasing hormone (TRH) (200 μg iv) and the dopamine antagonist, metoclopramide (MC; 10 mg iv) were studied successively, 1 h apart. Nine healthy women were studied with TRH-MC test and with another test in which MC alone was used or the drugs were given in opposite order. The preceding TRH injection did not affect the Prl responses to MC, nor did preceding MC affect the Prl response to TRH.
With the TRH-MC test, Prl responses to TRH and MC were significantly lowered in amenorrhoea (N = 8) and hyperprolactinaemia (N = 15) regardless of whether or not treated with bromocriptine, and to MC only in oligomenorrhoea (n = 11). In normoprolactinaemic galactorrhoea (N = 7) the responses were similar as in healthy women. The ratio between Prl responses to TRH and MC was significantly higher in women with bromocriptine-treated hyperprolactinaemia (1.06 ± 0.8, so) than in healthy controls (0.34 ± 0.13).
The capacity of pituitary lactotrophs to secrete Prl in response TRH and MC can be evaluated with a 2-h test which has potential for investigation of pituitary Prl dynamics in gynaecological endocrine disorders, particularly in amenorrhoea and hyperprolactinaemia.
Goitre size and outcome of medical treatment of Graves' disease
Authors: Laurberg Peter , Hansen Poul Erik Buchholtz , Iversen Eigil , Jensen Sigurd Eskjær , Weeke Jørgen 
Published: December 2008

Abstract. One hundred and twenty-four patients with newly diagnosed hyperthyroidism received a combined thionamid-thyroxine medical therapy for approximately 2 years. According to the estimated goitre size before therapy and the type of goitre the patients were divided into 4 groups: Graves' disease no goitre (n = 19). Graves' disease small goitre (n = 57), Graves' disease medium or large goitre (n = 23), multinodular goitre (n = 25). The median follow-up period after cessation of medication was 64 (range 11–141) months.
The remission rates in the different groups during follow-up were calculated using life table analysis. Graves' patients with no goitre or a small goitre had a significantly better outcome (remission % after 5 years 82.5 ± 15.4 (se) and 71.5 ± 7.8, respectively) than Graves' patients with a medium size or large goitre (remission % after 5 years 37.0 ± 11.1) (P <0.025). Most patients with multinodular goitre had a relapse within the first year after stop of medication (remission % after 5 years 15.5 ± 10.1). Hence patients with Graves' disease having a small thyroid gland should be treated medically while surgery or radioiodine may be a more reasonable choice in Graves' patients with medium size or large goitres. Medically treated patients with toxic multinodular goitres have a very small chance of prolonged remission if medication is stopped.
Plasma adrenocorticotrophin, cortisol and aldosterone responses to ovine corticotrophin-releasing factor and vasopressin in sheep
Authors: Pradier P. , Davicco M. J. , Safwate A. , Tournaire C. , Dalle M. , Barler J. P. , Delost P. 
Published: December 2008

Abstract. Ovine corticotrophin-releasing factor (oCRF) (1 μg/kg) and arginine vasopressin (AVP) (1 μg/kg) were injected iv in sheep, both separately and in combination. Plasma levels of immunoreactive ACTH (IRACTH), cortisol, and aldosterone were measured for 3 h after the injections. Mean levels before injections were 8 ± 4 pmol/l for ACTH, 7 ± 3 nmol/l for cortisol, and 28 ± 9 pmol/l for aldosterone. CRF caused a rapid rise in IR-ACTH and a peak level of 125 ± 52 pmol/l was obtained 15 min after injection. Highest values for cortisol and aldosterone levels were 40 ± 9 nmol/l and 64 ± 13 pmol/l, respectively, 30 min after injection. AVP also increased IR-ACTH (maximum level: 202 ± 77 pmol/l at 5 min) and aldosterone (128 ± 36 pmol/l at 15 min), whereas the cortisol increase was lower than after CRF. Simultaneous injection of CRF and AVP produced an addition of the IR-ACTH response (295 ± 82 pmol/l at 15 min), but the changes in cortisol levels were similar to those obtained after CRF alone and those in aldosterone levels resembled those induced by AVP alone.
Plasma Na and K, osmolality, and plasma renin activity (PRA) were not modified by either CRF or AVP. It is suggested that the increase in aldosterone levels after CRF could be mediated by ACTH and that after AVP by an IR-ACTH peptide with less effect on cortisol secretion.
Somatostatin, insulin and glucagon after arginine stimulation in active and treated acromegaly
Authors: Skare Ståle , Kriz Vera , Hanssen Kristian F. 
Published: December 2008

Abstract. Ten acromegalic patients, 28–71 years old, were compared with 10 normal controls, 21–39 years old. In another study, 7 patients with active acromegaly, 19–70 years old, were investigated before and 4–9 months following transsphenoidal adenectomy and radiation. They were all investigated following an arginine infusion (0.5 g/kg/20 min).
Although the mean plasma somatostatin (somatotrophin release inhibiting factor (SRIF)) was somewhat higher in acromegalic patients compared to normal controls (mean basal values 21 ± 3.8 and 16.6 ± 2.1 pmol/l, respectively), the difference was not significant. The patients had higher serum insulin (peak values 118 ± 23.9 and 63 ± 11.8 mU/1, respectively) and lower plasma glucagon (peak values 171 ± 29.0 and 310 ± 52.7 pmol/l, respectively).
Plasma SRIF increased during arginine infusion, but the concentrations were similar before and following the operation (mean basal values 18.2 ± 2.6 and 15.2 ± 2.3 pmol/l, respectively). Serum insulin was significantly higher before the operation (peak values 154 ± 38.8 and 91 ± 24.9 mU/1, respectively). Plasma glucagon was similar before and after the operation (peak values 143 ± 23.4 and 127 ± 22.7 pmol/l, respectively).
Plasma SRIF is similar in active acromegaly and normal controls, and in acromegaly before and following treatment, despite differences in serum growth hormone (GH), serum insulin and plasma glucagon. This points towards a modulating role for GH on plasma SRIF, possibly by affecting the other islet cell hormones.
Effect of an acute injection of melatonin on the basal secretion of hypophyseal hormones in prepubertal and pubertal healthy subjects
Authors: Lisoni P. , Resentini M. , Mauri R. , De Medici C. , Morabito F. , Esposti D. , Di Bella L. , Esposti G. , Rossi D. , Parravicini L. , Legname G. , Fraschini F. 
Published: December 2008

Abstract. It is well known that the pineal gland can modulate the secretion of pituitary hormones. Melatonin, the main hormone produced by the pineal gland, acts at the hypothalamic site, whereas hypophyseal sensitivity to melatonin seems to change with age. To investigate the influence of pubertal development on the role of the pineal gland in the regulation of the secretion of pituitary hormones, FSH, LH, Prl, TSH and GH responses to melatonin were evaluated in a group of 9 prepubertal and 10 pubertal healthy subjects of both sexes. Melatonin was given im at a dose of 0.2 mg/kg body weight at 3 p.m. Venous blood samples were drawn −20, 0, 20, 40, 60, 90, 120, 180 and 240 min, after melatonin injection. According to the same experimental protocol, venous blood samples were collected during a saline infusion on a separate occasion. FSH, LH, Prl, TSH and GH plasma levels were measured with RIA. In pubertal subjects, a significant rise in the mean Prl levels was seen 90 min after melatonin as compared with those during saline infusion. The Prl melatonin response area was significantly lower in prepubertal treated subjects and significantly higher in pubertal ones compared with the respective controls. The mean GH values showed a significant decrease 120 min after melatonin only in prepubertal subjects; no significant variations were seen in 8 of 10 pubertal subjects, whereas in the last 2 a marked increase was observed. Finally, under these conditions, melatonin did not influence the basal FSH LH and TSH levels.
These results seem to suggest that hypophyseal hormone reponses change with pubertal development.
Isolation, purification and culture of Sertoli cells from immature piglet testes
Authors: Renier G. , Gaulin J. , Gibb W. , Simard P. , Leung T. K. , Collu R. , Ducharme J. R. 
Published: December 2008

Abstract. Several studies suggest a role of Sertoli cells in the control of Leydig cell steroidogenesis. In order to verify this hypothesis, we have developed a system for the purification of pig Sertoli cells. These cells were then characterized by their morphological appearance in light and electron microscopy, their ability to bind [125I]follicle stimulating hormone (FSH) and their functional capacity as evaluated by adenosine 3',5' monophosphate (cAMP) accumulation and lactate production when in primary culture under basal and FSH-stimulated conditions.
Crude Sertoli cell suspensions from immature porcine testes were fractionated on discontinuous Percoll gradients (densities 1.025, 1.039, 1.055, 1.080 g/ml). Highly purified Sertoli cells were contained in the second band (d: 1.039) generated on the gradient. These cells demonstrated morphological and functional integrity as evidenced by binding specifically [125I] FSH and by responding to FSH stimulation (by an increased production of cAMP and lactate after 3 days in primary culture), but not to human chorionic gonadotrophin (hCG).
This preparation represents a useful model for the study of Sertoli cell functions and their interation with Leydig cells in the regulation of testicular steroidogenesis.
The effect of oestriol and tamoxifen on oestradiol induced prolactin secretion in anaesthetised rats
Authors: Gilna Paul , Martin Finian 
Published: December 2008

Abstract. In ovariectomized rats oestradiol and oestriol administered sc for 5 days increased basal plasma prolactin in a dose related manner to similar maximal values. The data fitted log dose-response curves. Oestradiol was about 12 times more potent than oestriol. These dose response relationships were retained on thyrotrophin releasing hormone (TRH) administration (50 ng iv, blood sampled 5 min post TRH). In addition, significantly higher maximal response values for both oestradiol and oestriol were now seen. The relative potency also increased in oestradiols favour.
We subsequently examined the effect of co-administering oestriol with oestradiol on plasma secretory responses to a single dose of oestradiol in young male rats: Oestriol (30 μg) potentiated increases in basal plasma prolactin, TRH stimulated prolactin secretion and radioimmunoassayable pituitary prolactin in rats in response to a single sc injection of oestradiol (10 μg). Tamoxifen, administered once also potentiated these responses to a single sc injection of oestradiol. However, if the tamoxifen was administered sequentially i.e. 48 and 24 h before or 48 and 24 h before and simultaneous with the oestradiol the potentiation was completely reversed.
Effects of angiotensin II infusion on the early morning surge of ACTH and on o-CRH-provoked ACTH secretion in normal man
Authors: Haller H. , Hensen J. , Bähr V. , Oelkers W. , Exner P. , Windfuhr L. 
Published: December 2008

Abstract. The question of whether elevated plasma angiotensin II (All) levels modulate ACTH secretion in man still awaits a definite answer. We performed two sets of experiments pertinent to that problem:
Seven healthy young males each received All (5 ng/kg/min) and sham infusions on different days in a randomized sequence from 03.00 h to 06.00 h in the morning, while plasma ACTH and cortisol were measured every 20 min. Mean blood pressure rose by about 10 mmHg during All infusion. Mean plasma ACTH levels were slightly higher with All than with sham infusion in every single individual (P <0.05). Differences in a pre- and post-infusion period were significant. Plasma cortisol levels were almost identical with or without All infusion. Nine healthy young males received All (5 ng/kg/min) or sham infusions on different days from 16.30 h to 20.00 h in a randomized sequence and a 100 μg o-CRH injection at 17.00 h. Plasma ACTH and cortisol were measured every 15 or 30 min between 16.30 h and 20.00 h. Mean blood pressure rose by about 14 mmHg during All infusion. The rapid increment and further change in plasma ACTH and cortisol was not significantly different between the All and sham infusion studies. Conclusions: The dose of All infused was probably just above the threshold of ACTH stimulation, although All plasma levels obtained were probably far above the physiological range. On the adrenal level, a vasoconstrictor effect of All may have prevented stimulation of cortisol. This may be different in states of sodium depletion with reduced vascular effects of AII. The CRH experiment supports the idea that All enhances hypothalamic CRH release rather than directly stimulating ACTH on the pituitary level.
Cannulation of the utero-ovarian vein in intact ewes: hormone concentrations and blood gas levels during the oestrous cycle and early pregnancy
Authors: Hooper S. B. , Walker D. W. , Thorburn G. D. 
Published: December 2008

Abstract. A technique for implanting and maintaining catheters in both utero-ovarian veins (UOV) of intact, conscious sheep has been developed. Both UOV catheters remained patent for more than 2 weeks in 72.7% of animals. In non-pregnant ewes, large pulses of PGF2α were observed in UOV plasma collected on days 13 to 16 of the cycle (frequency 1.3 ± 0.2/12 h; pulse height range 1.0–26.9 ng/ml). In contrast, on days 13 to 16 of gestation, significantly (P < 0.001) fewer pulses of PGF2α (frequency 0.42 ± 0.2/12 h) were observed in both UOVs of pregnant ewes, which were significantly (P < 0.001) smaller in amplitude (pulse height range 1.4–4.9 ng/ml). The maintenance of the corpus luteum (CL) during early pregnancy may therefore directly result from a decreased uterine PGF2α release.
During the luteal phase (day 4–12), the PO2 of UOV blood draining an ovary containing a CL (UOV/CL) was significantly higher than blood in the contralateral UOV (P <0.001). By days 15 and 16 of the cycle, the PO2 of UOV/CL blood had decreased and was not significantly different to that observed in the contralateral UOV (P >0.1). On day 17, the PO2 of blood in both UOVs was elevated significantly compared to levels observed on the two preceding and the two following days (P < 0.001). We consider that the higher PO2 in UOV/CL blood resulted from a very high luteal blood flow, and that the decrease on days 15 and 16 of the cycle resulted from a decline in luteal blood flow during luteolysis. The subsequent increase in PO2 of blood from both UOVs on day 17 was considered to result from an increased uterine blood flow.
Modulation of LH-secretion in ovariectomized ewes by constant infusions of oestradiol and 4-hydroxyoestradiol: effects of varying infusion times and of high oestrogen doses
Authors: Emons G. , Schuppe H. , Peter M. , Brack C. , Ball P. 
Published: December 2008

Abstract. Ovariectomized ewes were infused for different times (2–24 h) during the breeding season (September to Februray) with oestradiol (E2, 2 μg/h) or the catecholoestrogen 4-hydroxyoestradiol (4-OHE2, 10 μg/h). At these infusion rates comparable plasma levels of E2 and 4-OHE2 were obtained when steady state was reached after 3 h (E2: 20 ± 4 pg/ml; 4-OHE2: 22 ± 3 pg/ml). When E2 was infused for at least 6 h, all animals had significant LH-surges, starting 14-16 h after the beginning of oestrogen treatment, even when E2 was infused for up to 24 h. 4-OHE2, however, had only to be infused for 4 h to induce significant LH-surges in all animals tested. When E2 was infused for 12 h at a rate of 100 μg/h, the LH-surges in these ewes were significantly lower than the LH-surges in the same animals treated for 12 h with E2at a rate of 2 μg/h.
These data indicate:
Once E2 has been administered at a specific infusion rate for a critical time period of 6 h, LH-surges occur, no matter whether the E2-infusion is continued or stopped. For the catecholoestrogen 4-OHE2 this critical time period amounts only to 4 h, if comparable plasma levels of either oestrogen are achieved. This might hint at a prolonged intracellular action of 4-OHE2 as compared to E2. At extremely high infusion rates of E2 (100 μg/h for 12 h) the positive oestrogen effect is significantly impaired, a finding supporting the concept of a bell-shaped dose-response relationship between oestrogens and their positive effect on LH-secretion.
Growth hormone response to growth hormone-releasing hormone in normal and uraemic children. Comparison with hypoglycaemia following insulin administration
Authors: Bessarione D. , Perfumo F. , Giusti M. , Ginevri F. , Mazzocchi G. , Gusmano R. , Giordano G. 
Published: December 2008

Abstract. The uraemic syndrome is characterized by several endocrinological disturbances. This study was undertaken in order to evaluate the GH response to growth hormone-releasing hormone (GRH) in children with chronic renal failure (CRF) and to compare the results with those observed after insulin hypoglycaemia. Twenty-two children with CRF, 10 undergoing continuous ambulatory peritoneal dialysis (CAPD) and 12 on conservative treatment (CT), age ranges 2–15 years, were studied and the data were compared with those from 14 children with normal renal function and normal hormonal behaviour, affected by short stature (NC), and those form 13 healthy adult volunteers (NA). The GRH test (1 μg/kg body weight, iv) was carried out in 8 CAPD, 8 CT, 9 NC and 10 NA subjects. The blood samples were taken every 30 min for 3 h in CAPD and CT and for 2 h in NC and NA starting at 09.00 h. The following hormones were measured: GH, LH, FSH, Prl, TSH and cortisol (F). The insulin test (0.1 U/kg body weight, iv) was carried out in 5 CAPD, 5 CT, 10 NC and 9 NA on blood samples taken every 30 min for 2 h, measuring GH and glycaemia. No adverse effects were observed after the infusion of GRH.
GRH administration induced a prompt response in all subjects, but GH plasma levels were significantly higher in uraemic children than in adults (peak value of 43.5 ± 8.2, 45.0 ± 8.4, 27.8 ± 6.0; 13.5 ± 2.6 μg/ml in CAPD, CT, NC and NA, respectively). The secretory areas were significantly narrower in NC (P < 0.05) and NA (P < 0.01) than in CAPD, and in NA than in CT (P < 0.01). The GH response to insulin did not differ in the 4 groups. The secretory area in CAPD and CT was wider after GRH than after insulin. The GH peak value of CAPD and NC was significantly higher after GRH than following insulin. No significant variation in TSH, LH and FSH was observed after the infusion of the neuropeptide, whereas Prl and F showed a reduction. The behaviour of Prl and F in NA and NC was similar after placebo and GRH.
Our data show: a) There is a greater response of GH to GRH in children than in adults; b) compared with the insulin test, GRH stimulation seems to be a reliable means of evaluating GH secretion both in normal and uraemic children owing to the absence of qualitatively different responses and to the freedom from the adverse effects or risks which follow insulin infusion; c) GRH administration does not induce any significant variation on other hypophyseal hormones and the reduction of Prl and F seems to follow the normal sleep-wake and circadian behaviour.
The role of androstenedione and testosterone in the reproduction and antler growth of a male white-tailed deer
Authors: Bubenik G. A. , Pomerantz D. K. , Schams D. , Smith P. S. 
Published: December 2008

Abstract. Seasonal levels of androstenedione and testosterone were investigated in plasma of mature intact and castrated male white-tailed deer. In four intact bucks, androstenedione concentrations were low in February and March (around 1 nmol/l) and then increased significantly (P < 0.05) from April to November (peak 2.34 nmol/l). Testosterone remained low (below 3.5 nmol/l) from February to August and then rose significantly (P < 0.01) till November (peak 36.78 nmol/l). Both hormones declined from November to February. In three castrates, androstenedione levels remained virtually unchanged (averaging around 0.5 nmol/l) between January and September. After a rapid significant increase (P < 0.05) till November (peak value 2.45 nmol/l), androstenedione concentrations declined quickly to a baseline level. Testosterone in castrates remained around 0.3 to 0.7 nmol/l for most of the year with a non-significant peak (1.45 nmol/l) in October.
These data indicate that the spring and summer increase in androstenedione in the intact deer is of testicular origin; the fall peak, however, may be a result of increased production in the adrenal glands.
It can be speculated that the increase in androstenedione in the blood of the male deer during the spring may be responsible for the seasonal initiation and support of antler growth as well as being supportive to the re-activation of the reproductive system.
Phenobarbital enhances pituitary LH release induced by LRH pulses in the ovariectomized rat
Authors: Lambalk C. B. , van Dieten J. A. M. J. , de Koning J. , Schoemaker J. , van Rees G. P. 
Published: December 2008

Abstract. In the ovariectomized (OVX) rat, the plasma LH response was measured to a pulse of LRH (1.25 or 5 ng/100 g body weight, ia) given before and 1 h after ip administration of phenobarbital (80 mg/kg body weight). The LH response to the LRH pulses was increased 1 h after phenobarbital.
In a second experiment, the pituitary LH content of OVX rats was measured 1 h after administration of phenobarbital or saline. No difference in pituitary LH content was found.
It is concluded that in the OVX rat, phenobarbital increases the response to a pulse of LRH, presumably by suppressing endogenous pulsatile LRH. This, together with results of earlier experiments, further supports the hypothesis that under conditions where endogenous pulsatile LRH is present, there is always a certain degree of pituitary desensitization or refractoriness and that the removal of this endogenous LRH leads to recovery of pituitary sensitivity to LRH.