bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thyroid function in adrenocortical insufficiency during withdrawal and re-administration of glucocorticoid substitution
Authors: Grubeck-Loebenstein B. , Vierhapper H. , Waldhäusl W. , Nowotny P. 
Published: December 2008

Abstract. The regulatory function of glucocorticoids on thyroid hormone concentrations was studied in patients with adrenocortical insufficiency (ACI, n = 8) and in healthy subjects (n = 6). In patients with ACI withdrawal of glucocorticoid substitution for 84 h led to an increase in serum concentrations of total triiodothyronine (TT3) from 110 ± 20 to 133 ± 22 ng/dl and a decrease of serum reverse-T3 (rT3) from 23 ± 6 to 18 ± 6 ng/dl, whereas subsequent administration of dexamethasone (0.5 mg po q.i.d. for 3 days) induced a fall in TT3 (129 ± 22 to 88 ± 16 ng/dl) and a rise in rT3 (17 ± 5 to 37 ± 11 ng/dl) concentrations. Serum levels of total thyroxine (TT4) were unchanged by either withdrawal or re-administration of glucocorticoids. Basal plasma thyrotrophin (TSH) concentrations were unchanged by glucocorticoid withdrawal and fell from 2.2 ± 1.5 to 1.1 ± 0.8 mU/l during subsequent dexamethasone therapy.
In healthy subjects a decrease of TT3 (89 ± 8 to 69 ± 8 ng/dl) and an increase in rT3 (19 ± 5 to 32 ± 8 ng/dl) concentrations were seen after stimulation of endogenous cortisol production by prolonged infusion of ACTH1-24 (0.5 mg, t = 8 h on 2 consecutive days), whereas concentrations of TT4 remained unchanged. During subsequent administration of dexamethasone serum level of both, TT3 and rT3 returned to basal levels. Thus, changes in thyroid hormone concentrations are induced by alterations of substitution therapy in patients with ACI. In healthy subjects the application of 2 mg dexamethasone/day following prolonged maximal stimulation of endogenous cortisol by iv ACTH may represent a state of relative glucocorticoid deficiency, thus explaining the observed hormonal changes, which are inverse to those generally induced in healthy man by endogenous or exogenous glucocorticoids.
Tubero-infundibular dopaminergic function in cirrhotic patients: evaluation by nomifensine and domperidone
Authors: Monza G. C. , Lampertico M. , Locatelli S. , Sali L. , Cocchi D. 
Published: December 2008

Abstract. Cirrhotic patients reportedly show alterations of anterior pituitary hormone secretion, which may reflect an underlying defective central neurotransmitter function. In this study, we have investigated the catecholaminergic control of prolactin (Prl) and growth hormone (GH) secretion in cirrhotic patients by means of an indirectly acting dopamine (DA) and norepinephrine agonist, nomifensine (Nom), and a DA receptor antagonist, domperidone (Dom).
Basal GH levels were higher in the 12 female and male cirrhotic patients than in the 12 age- and sex-matched normal controls, while no difference was present in basal Prl values.
Administration of Nom (200 mg po) suppressed basal Prl levels (at least 30% inhibition at three consecutive times post-drug administration) in 6/12 controls and in 6/12 cirrhotic patients, the frequency of negative responses not being different between the two groups. Nom induced a slight elevation of GH levels in controls, and evoked a more marked and sustained GH increase in cirrhotic patients.
Administration of Dom (4 mg iv) induced similar Prl increments in 6 male controls and 6 male cirrhotic patients.
Normal Prl responsiveness to Nom and Dom points to the existence of preserved tubero-infundibular DA function and modulation of pituitary DA receptors in the cirrhotic patients investigated. Higher GH responsiveness to Nom is compatible with a different bioavailability of the drug.
A sensitive method for assaying thyroid stimulating immunoglobulins of Graves' disease: use of the guanyl nucleotide-amplified thyroid adenylate cyclase assay
Authors: Macchia E. , Carayon P. , Fenzi G. F. , Lissitzky S. , Pinchera A. 
Published: December 2008

Abstract. The purpose of this study was to develop and validate a sensitive method for evaluating adenylate cyclase stimulation by thyroid-stimulating antibodies (TSAb), based on the measurement of thyroid membrane adenylate cyclase activity in the presence of a non-hydrolyzable GTP analogue, guanyl-5'-yl imidodiphosphate (Gpp(NH)p).
The addition of Gpp(NH)p (10−5 m) produced a 10-fold increase of the sensitivity of the system for both TSH and TSAb. Immunoglobulin G preparations from sera of 30 patients with Graves' disease were tested for the adenylate cyclase stimulation either in the presence or in the absence of Gpp(NH)p: a significant stimulation was observed in 27/30 patients when the GTP analogue was added to the system, while only 20/30 patients were positive in the absence of the nucleotide. The advantage of Gpp(NH)p addition was also evident in a large series which included 57 patients with Graves' disease, 15 with Hashimoto's thyroiditis or primary myxoedema and 22 normal subjects. In fact, 88% of patients with Graves' disease resulted positive, while no significant stimulation was elicited by Hashimoto's thyroiditis, primary myxoedema and by normal immunoglobulins.
The sensitivity achieved in our system which employs thyroid plasma membranes was similar to that obtained by other investigators with the use of thyroid slices or thyroid cells in primary culture. Furthermore, methods based on thyroid plasma membranes are supposed to have a better reproducibility, since the same tissue preparation, if appropriately stored, may be used in several different tests.
Insulin stimulation of somatomedin A production in monolayer cultures of rat hepatocytes
Authors: Kogawa Megumi , Takano Kazue , Asakawa Kumiko , Hizuka Naomi , Tsushima Toshio , Shizume Kazuo 
Published: December 2008

Abstract. The effect of insulin on the generation of somatomedin by a monolayer culture of rat hepatocytes was investigated. Release of somatomedin into the medium of cultured hepatocytes was observed for at least three days, as determined by a radioreceptor assay for somatomedin A. The addition of 1–100 μg/ml insulin to the medium caused dose-related increases in somatomedin A in the conditioned medium for up to three days. The conditioned medium also stimulated DNA synthesis in human fibroblasts.
To investigate hormone degradation by hepatocytes, labelled somatomedin A or insulin was added to the medium and the degradation was examined by trichloroacetic acid (TCA) precipitation, and gel chromatography. Although [125I]somatomedin A was slightly degraded even after 24 h of incubation, [125I]insulin was degraded within 6 h and the TCA precipitation at 24 h was 15% only. This degradation of hormones was inhibited by 1 mm bacitracin. Insulin stimulation of somatomedin production was significantly increased to 131.2% as compared with cultures without bacitracin.
The molecular size of the somatomedin released into the medium was greater than that of purified somatomedin, suggesting that this somatomedin is bound to carrier proteins.
Studies on the mechanism of acute glucose-induced aldosterone suppression. Role of corticotrophin
Authors: Ferrier Claudia P. , Bianchetti Mario G. , Beretta-Piccoli Carlo , Link Ladislav , Bachman Claude , Weidmann Peter 
Published: December 2008

Abstract. A possible role of corticotrophin in mediating the acute glucose-induced suppression of plasma aldosterone was assessed in two groups of normal subjects (group A, N = 9 and group B, N = 10), by studying the effects of a standard oral glucose loading test on plasma concentrations of glucose, insulin, cortisol, potassium, aldosterone and renin activity, a) under basal conditions (groups A and B), b) after 2 days of dexamethasone (0.5 mg/6 h) (group A), c) after 8 weeks of treatment with the diuretic indapamide, 2.5 mg/day (group B) and d) after additional 2 days of combined administration of indapamide and dexamethasone (0.5 mg/6 h) (group B). In addition, the spontaneous daytime related variations of these parameters were assessed in group A in a control study without glucose loading. Under basal conditions, the acute increase in plasma glucose and insulin was accompanied by a significant decrease of plasma potassium (P < 0.01), cortisol (P < 0.01) and by a slight increase in plasma renin activity. None of these changes occurred in the control experiment without glucose loading. Dexamethasone caused a significant decrease in pre-loading plasma aldosterone. Indapamide caused a significant decrease in pre-loading plasma potassium and a marked stimulation of renin and aldosterone. After combined indapamide-dexamethasone administration, pre-loading plasma aldosterone decreased to control values. Glucose loading under dexamethasone or combined indapamide-dexamethasone administration caused a similar suppression of plasma aldosterone as observed under control conditions.
These findings suggest that corticotrophin does not play an important role in mediating the acute aldosterone inhibitory effect of glucose loading. However, corticotrophin may contribute to the maintenance of the secondary hyperaldosteronism induced by diuretic treatment.
Changes in gonadotrophin binding to rat ovaries during sexual maturation
Authors: Uilenbroek J. Th. J. , van der Linden R. 
Published: December 2008

Abstract.
Changes in LH and FSH binding to rat ovaries during sexual maturation were measured by in vitro binding assay and autoradiography. Ovaries were obtained from rats at various ages ranging from 5 till 35 days of age. Animals older than 35 days of age were classified in three groups: anoestrus (uterine weight below 60 mg), early pro-oestrus (uterine weight 60–120 mg) and pro-oestrus (uterus distended with fluid). Measurements were made of specific binding of radioiodinated hCG and rFSH to ovarian homogenates (day 5–35) and to granulosa cells isolated from the largest follicles (day 35–pro-oestrus).
The earliest age at which specific hCG and FSH binding could be demonstrated was day 11. Thereafter hCG binding to ovarian homogenates, expressed in cpm/μg DNA, increased with age. Specific binding of hCG to granulosa cells increased from 1000 cpm/μg DNA at day 35 to 4000 cpm/μg DNA at pro-oestrus. FSH binding to ovarian homogenates increased till day 21 and remained fairly constant thereafter.
Autoradiography revealed the presence of hCG binding to interstitial tissue and thecal cells. hCG binding to granulosa cells was only found in large pre-ovulatory follicles present at early pro-oestrus and pro-oestrus. FSH binding was observed to granulosa cells of all types of follicles, but not to interstitial and thecal cells.
The results demonstrate that during sexual maturation FSH binding to granulosa cells remains constant, whereas LH binding to interstitium and theca and ultimately to granulosa cells increases with age suggesting an increased responsiveness of the ovaries to LH.
Treatment of hyperprolactinaemic patients with pergolide
Authors: L'Hermite Marc , Debusschere Pierre M. , Gillet Clémentine , Deschepper Christian 
Published: December 2008

Abstract. Eighteen hyperprolactinaemic patients were orally treated for up to 16 months with pergolide mesylate, a new potent long-lasting dopaminergic ergot derivative. In all cases, Prl normalization (< 25 ng/ml) was achieved at a once-a-day dose of 50–300 μg. All women recovered and/or exhibited normal menstrual function. Among the 6 women wishing to become pregnant, 4 of them conceived within 4 months; there were other causes for infertility than hyperprolactinaemia in the 2 other couples.
A macroprolactinoma man experienced important improvement in well-being as well as objective regression of his visual fields defect. This suggests a shrinkage effect of pergolide on the tumoural process. Another man regained normal potency and normal testosterone within 2 weeks.
While 10 patients were completely free of any side effect, 7 experienced transiently mild gastro-intestinal side effects or postural hypotension. Only one patient discontinued her treatment because of dizziness.
The present study demonstrates the high potency, the good tolerance and the excellent efficacy of pergolide in the treatment og hyperprolactinaemia.
No acute effect of pimozide on the plasma GH levels in acromegaly
Authors: Nortier J. W. R. , Croughs R. J. M. , Donker G. H. , Thijssen J. H. H. , Schwarz F. 
Published: December 2008

Abstract. In 34 acromegalic patients either untreated or inadequately treated by surgery and/or radiotherapy the plasma GH levels and plasma Prl levels were determined during 8 h after the acute administration of the dopamine agonist bromocriptine and during 150 min after the administration of the dopamine antagonist pimozide.
A 50% or more suppression of the basal GH levels was arbitrarily defined as a positive response. Seventeen patients displayed a positive response to bromocriptine, 17 patients displayed a negative response to bromocriptine. Plasma Prl levels were elevated in 6 of 17 bromocriptine responders and in 2 of 17 bromocriptine nonresponders. There was no difference in the plasma GH response to pimozide administration in the patients with a positive or a negative GH response to bromocriptine.
With one exception there was in no patient a positive GH response to pimozide. In further experiments the plasma GH response to pimozide was measured during 11 h in 6 bromocriptine sensitive and 6 bromocriptine insensitive patients. Again no difference was found between bromocriptine responders and non-responders. There was also no difference in the Prl response to bromocriptine or pimozide between GH responders and GH non-responders. The Prl response to pimozide was blunted in comparison to a control group.
The present study does not lend support to the idea that there is a fundamental difference in the degree of hypothalamic dopaminergic control of GH or Prl secretion between bromocriptine sensitive and bromocriptine insensitive patients with acromegaly.
Computerized cranial tomography in the evaluation of pituitary tumours in rats
Authors: Casanueva Felipe F. , Gordon William L. , Friesen Henry G. 
Published: December 2008

Abstract. The use of the rat as an animal model in studies of pituitary tumours has been hampered by the great individual variation and the necessity of killing the animal to assess the development and progression of tumour growth. A study was designed to determine whether computed tomography (CT) could be used to monitor the growth of pituitary tumours in female Sprague-Dawley rats. Animals were injected with oestradiol valerate 2 mg/3 weeks sc, an amount known to lead to development of pituitary tumours (from 45 to 378 mg pituitary weight). Control rats were treated with vehicle alone.
Anaesthetized rats injected with contrast were studied by computerized axial tomography and the single CT scans (coronal cuts) were correlated with direct anatomical measurements obtained after pituitary dissection. All pituitaries weighing more than 54 mg were detected by the CT scanner. A good correlation between measurements made after anatomical dissection was found in the two main axes of the coronal cuts.
In conclusion, CT scanning can be used for assessment of pituitary tumour size in the rat. This technique should be especially helpful in studies where individual evaluation and/or repeated measurements over time are necessary.
The effect of propylthiouracil and methimazole on the peripheral conversion of thyroxine to 3,5,3'-triiodothyronine in athyreotic thyroxine-maintained rats
Authors: van Doom J. , Roelfsema F. , van der Heide D. 
Published: December 2008

Abstract. The effect of prolonged oral administration of PTU and MMI on the local conversion of T4 to T3 was studied in T4-maintained athyreotic rats. For this purpose the rats were equilibrated with [125I]T4 and [131I]T3 by means of continuous iv infusions.
PTU treatment reduced the MCR of both T4 and T3, as well as the T3 levels in plasma, muscle, liver, kidney and cerebellum. In the cerebral cortex the total intracellular T3 concentration was not affected, while in the pituitary it even increased. The amount of T3 derived from local conversion of T4 to T3 (LcT3(T4)) was reduced in the liver. PTU treatment did not influence Lc T3(T4) in the cerebellum, but did cause an increase in the amount of T3 derived from this source in the cerebral cortex and the pituitary gland (both the homogenate and the nuclear fraction). The results indicate that in contrast to that in liver, local T3 production in the brain and pituitary must occur predominantly via a pathway which is not inhibited by PTU.
In MMI-treated rats the total T3 concentration in the cerebral cortex and cerebellum was not altered, whereas both the MCR of T3 and the T3 levels in plasma and various other tissues were elevated. The relative contribution of Lc T3(T4) increased in liver and was reduced in the cerebral cortex, cerebellum and pituitary gland.
In all experiments in liver the contribution of Lc T3(T4) to nuclear T3 was negligible, whereas this was not the case for the other hepatic subcellular fractions. As in liver, virtually all renal nuclear T3 was derived from plasma. The present findings suggest that the production of T3 in liver and kidney, and its subsequent release into the blood, may provide a mechanism for the regulation of plasma T3 levels but is not a direct source of their nuclear T3.
In the pituitary gland and the brain local T4 to T3 conversion functions as a source of T3 for the control of local utilization. In this respect the maintainance of constant T3 levels in the brain might be important.
These differences among tissues suggest that different mechanisms are involved in T4 5'-deiodination.
Effect of hypo- and hyperthyroidism on the balance between helper and suppressor T cells in rats
Authors: Pacini F. , Nakamura H. , DeGroot L. J. 
Published: December 2008

Abstract. The proportion of total, helper and suppressor T lymphocytes among mononuclear cell preparations from blood and spleen of rats made hypo- and hyperthyroid was measured using three monoclonal antibodies specifically directed against total, helper and suppressor T cells.
Compared to normal rats, hypothyroid (thyroidectomized or treated with 6-propyl-2-thiouracil (PTU)) rats had a decreased proportion of suppressor T cells in the spleen, which produced an increase in the helper/suppressor T cells ratio. The opposite alterations (increased suppressor T cells and decreased ratio) was found in the blood of the same animals. Triiodothyronine (T3) added to PTU in the drinking water prevented these alterations. Animals treated with high doses of T3 for 17 days did not develop any alteration either in the proportions or in the ratio of helper/suppressor T cells. Our results suggest that hypothyroidism but not hyperthyroidism alters the normal balance between helper and suppressor T cells in rats.
Insulin release in aging: the role of glyceraldehyde
Authors: Premdas Francis H. , Molina Joseph M. , Lipson Loren G. 
Published: December 2008

Abstract. Glucose-stimulated insulin release is decreased from pancreatic islets of older rats. The mechanism for this and its relationship to the hyperglycaemia of aging remain to be fully elucidated. We have recently shown that adenylate cyclase activity is reduced in islets from older rats and this might, in part, account for the decreased insulin release. It has been shown, however, that islet glucose oxidation is also reduced in aging. In an attempt to gain further insight into the biochemistry of this age-related decrease in insulin release, we investigated D-glyceraldehyde-stimulated insulin secretion.
Simultaneous experiments were performed on islets from 2 and 13 month old rats to determine insulin release in response to 2.8 mM or 16.7 mm d-glucose or 2.8 mm d-glucose + 2.5, 5.0, 7.5, 10.0 or 14.4 mm d-glyceraldehyde. Islets were incubated for 30 min at 37°C in a metabolic shaker bath and the media were then assayed for insulin by conventional radioimmunoassay.
Insulin secretion in response to 2.8 mm d-glucose was similar in the two groups of islets (9.8 ± 0.9 pg insulin islet−1min−1 from old vs 8.9 ± 1.0 from the young control rats, P < 0.2). Insulin release was diminished by 32% from islets of older rats in the presence of 16.7 mm d-glucose compared with islets from young control rats (84.0 ± 5.6 pg insulin islet−1min−1 from older animals vs 123.5 ± 10.7 from controls, P < 0.001). In the presence of 2.8 mm d-glucose + all concentrations of d-glyceraldehyde used, insulin release was similar from islets of older and young rats.
From these results, it appears that the diminished insulin release from islets of older rats involves not only changes in the adenylate cyclase system, but also may involve changes in glucose metabolism at a rate-limiting step in stimulus-secretion coupling before the metabolism of the trioses.
Sodium valproate and cyproheptadine may independently induce a remission in the same patient with Cushing's disease
Authors: Koppeschaar H. P. F. , Croughs R.J. M. , Thijssen J. H. H. , Schwarz F. 
Published: December 2008

Abstract. A patient with Cushing's disease was unsuccessfully treated by pituitary surgery and external pituitary irradiation.
One year later sodium valproate treatment induced a remission and finally hypocorticism developed. After drug withdrawal hypercoticism recurred. Treatment with cyproheptadine again induced hypocorticism necessitating corticosteroid substitution therapy. Biochemical characteristics of this patient included responsiveness to bromocriptine and cyproheptadine in acute tests. The study demonstrates that sodium valproate and cyproheptadine may both be effective independently in the treatment of the same patient with Cushing's disease. It is proposed that the disease is due to an ACTH producing tumour of pituitary intermediate lobe origin.
Glucose, growth hormone, somatomedin, cortisol and ACTH changes in the plasma of unanaesthetised pig foetuses following intravenous insulin administration in utero
Authors: Spencer G. S. G. , Garssen G. J. , Colenbrander B. , Macdonald A. A. , Bevers M. M. 
Published: December 2008

Abstract. Insulin tolerance tests were carried out in chronically catheterised foetal pigs. The experiment was carried out 7 days after catheterisation. The foetuses were, therefore, considered to be free from the effects of anaesthetics and stress. Under these conditions growth hormone levels were high compared with post-natal growth hormone levels but, under the favourable conditions in this study, both growth hormone and ACTH levels were lower than those found in anaesthetised or stressed foetuses. By contrast, cortisol levels were somewhat higher than those mentioned in previous reports. Somatomedin activity measured by post-natal cartilage bioassay was low.
Following iv insulin administration there was a marked depression in plasma glucose (P < 0.01), an elevation in growth hormone (P < 0.05) and an increase in ACTH (P < 0.01). Levels of cortisol and somatomedins did not change significantly. From these data it is concluded that insulin is an hypoglycaemic factor in the foetal pig and that, for the most part, the foetal pig pituitary responds to an insulin challenge in a similar way to the post-natal pig.