Showing papers in "European Journal of Endocrinology in 1997"

Thyroid volume and urinary iodine in European schoolchildren: standardization of values for assessment of iodine deficiency

Abstract: Up to 1992, most European countries used to be moderately to severely iodine deficient. The present study aimed at evaluating possible changes in the status of iodine nutrition in 12 European countries during the past few years. Thyroid volume was measured by ultrasonography in 7599 schoolchildren aged 7-15 years in one to fifteen sites in The Netherlands. Belgium, Luxemburg, France, Germany, Austria, Italy, Poland, the Czech and Slovak Republics, Hungary and Romania. The concentrations of urinary iodine were measured in 5709 of them. A mobile unit (ThyroMobil van) equipped with a sonographic device and facilities for the collection of urine samples visited all sites in the 12 countries. All ultrasounds and all urinary iodine assays were performed by the same investigators. The status of iodine nutrition in schoolchildren has markedly improved in many European countries and is presently normal in The Netherlands, France and Slovakia. It remains unchanged in other countries such as Belgium. There is an inverse relationship between urinary iodine and thyroid volume in schoolchildren in Europe. Goiter occurs as soon as the urinary iodine is below a critical threshold of 10 micrograms/dl. Its prevalence is up to 10 to 40% in some remote European areas. This work produced updated recommendations for the normal volume of the thyroid measured by ultrasonography as a function of age, sex and body surface area in iodine-replete schoolchildren in Europe. This study proposes a method for a standardized evaluation of iodine nutrition on a continental basis, which could be used in other continents.

Glucocorticoid osteoporosis--mechanisms and management.

Abstract: Glucocorticoids are potent osteopenic agents, producing negative calcium and bone balance via actions at many sites. The most significant adverse effects of glucocorticoid drugs on the skeleton are probably a direct inhibition of matrix synthesis by the osteoblast, reductions in calcium absorption in both the gut and the renal tubule, and the production of hypogonadism, particularly in men. Reductions in bone density of 10-40% result, the loss being more marked in trabecular bone and in patients receiving a high cumulative dose of the steroid. Fractures occur in about 30% of individuals who take these drugs for an average of 5 years. Bone loss is reversible when glucocorticoid treatment is withdrawn. Bone density can also be increased by sex hormone replacement in those with demonstrable deficiency, by bisphosphonates, and possibly by vitamin D metabolites. All patients treated with glucocorticoids for more than 6 months should be considered for bone densitometry and be offered appropriate drug treatment if values are towards the lower end of the young normal range or if there is already evidence of fractures occurring after minimal trauma. With this approach, the significant morbidity associated with steroid osteoporosis might be substantially avoided.

Increased fracture frequency in adult patients with hypopituitarism and GH deficiency

Abstract: Fracture frequency was studied in 107 hypopituitary patients with GH deficiency (GHD) (69 men, mean age 53 years, range 18-74 and 38 women, mean age 54 years, range 31-73). Routine hormonal replacement therapy was given, except GH. Five male patients and 15 female patients with untreated hypogonadism were allocated to a separate group. The mean duration of hypopituitarism was 13.4 years. The prevalence of a history of fractures was assessed using questionnaires. A subsample of the Goteborg WHO MONICA Project was used as a reference population (n = 323). The total fracture frequency was threefold higher (P < 0.001) in patients (24.1%) compared with controls (8.7%) (odds ratio 3.49) (1.85-6.56; 95% confidence intervals). In men (n = 64) the fracture frequency was 25.0%, compared with 7.8% among the controls (P < 0.001). In women (n = 23) the fracture frequency was 21.7%, compared with 9.5% among the controls (P = 0.08). The odds ratios for fracture frequency were 3.97 (1.81-8.40; 95% confidence intervals) and 2.64 (0.89-7.81; 95% confidence intervals) in men and women respectively. In conclusion, adult hypopituitary patients with GHD had a threefold increased fracture frequency compared with controls. Further studies are needed to ascertain whether long-term recombinant human GH treatment can reduce the fracture rate in hypopituitary patients with GHD.

Regulation of the uncoupling protein gene expression.

Abstract: Uncoupling protein (UCP) is essential to the thermogenic function of brown adipose tissue (BAT). The thermogenic role of this protein is due to its capacity to uncouple oxidative phosphorylation in a regulated manner. The thermogenic potential of BAT is determined by its content of UCP. The gene encoding this protein is under complex regulation. Catecholamines, via cAMP, thyroid hormone and retinoic acid, directly stimulate the gene acting upon an upstream (-2.28/-2.49 kb) enhancer sequence, but cAMP may act upon other sequences of the gene as well. CCAAT enhancer binding proteins and peroxisome proliferation activator receptor (PPAR) gamma 2 have also been implicated in the regulation of the gene acting on discrete sequences. While the thyroid hormone response and retinoic acid response elements (TRE and RARE) have been well defined, the cAMP response elements (CRE) remain elusive. The two TREs are 27 bp apart between -2.33 kb and -2.39 kb. The synergism between cAMP and thyroid hormone seems to reside in a 39 bp sequence downstream (-2.28/-2.32 kb). The most important CRE, the RARE, a cell-specific enhancer and a putative PPAR element are all concentrated in a 90 bp regulatory element of great complexity (-2.40/-2.49 kb). Other hormones, such as insulin and glucocorticoids, and IGF-I also modulate the expression of the gene but their effects seem to be largely indirect. Understanding the regulation of the UCP gene expression may facilitate the development of interventions in obesity and related disorders.

Calcium-regulating hormones and parathyroid hormone-related peptide in normal human pregnancy and postpartum: a longitudinal study

Abstract: Objectives: To evaluate calcium-regulating hormones and parathyroid hormone-related peptide (PTHrP) in normal human pregnancy and postpartum in women not deficient in vitamin D. Design: A prospective longitudinal study was conducted in pregnant Saudi women during the course of pregnancy (n o 40), at term and 6 weeks postpartum (n o 18). Maternal concentrations of serum calcidiol and calcitriol were determined, together with those of serum intact-parathyroid hormone (PTH), PTHrP, calcitonin, osteocalcin, human placental lactogen (hPL), prolactin, vitamin D binding protein, alkaline phosphatase, calcium, phosphate and magnesium. A group of non-pregnant women (n o 280) were included for comparative purposes. Results: The calcidiol concentrations decreased (mean6S.D.) significantly from 54610 nmol/l in the first trimester to 3368 nmol/l in the third trimester (P < 0:001) and remained decreased at term and postpartum (both P < 0:001). The calcitriol concentration increased through pregnancy, from 69617 pmol/l in the first trimester to 333683 pmol/l at term (P < 0:001). Intact-PTH concentrations increased from 1.3160.25 pmol/l in the first trimester to 2.2660.39 pmol/l in the second trimester, but then declined to values of the first trimester and increased significantly postpartum (4.0260.36 pmol/l) (P < 0:001). PTHrP concentration increased through pregnancy from 0.8160.12 pmol/l in the first trimester to 2.0160.22 pmol/l at term and continued its increase postpartum (2.6360.15 pmol/l) (P < 0:001). Significant positive correlations were evident between PTHrP and alkaline phosphatase up to term (r o 0:051, P < 0:001) and between PTHrP and calcitriol (r o 0:46, P < 0:001), osteocalcin (r o 0:23, P < 0:05) and prolactin (r o 0:41, P < 0:05) during pregnancy. Osteocalcin started to increase from 0.1360.01 nmol/l in the second trimester, through pregnancy and postpartum (P < 0:001). Calcitonin was increased more than twofold by the second trimester compared with the first trimester (P < 0:001) and subsequently decreased (P < 0:001). Prolactin concentrations were significantly greater in the second (672461459 pmol/l) and third (839462086 pmol/l) trimesters compared with values before pregnancy (P < 0:001). hPL increased throughout the course of pregnancy, reaching a maximum at term (7.6162.57 mIU/ml). There was no direct correlation between serum calcitriol concentrations during pregnancy and serum prolactin (r oπ 0 :12, P < 0:19) or serum hPL (r o 0:17, P < 0:21). Significant changes were observed in the serum concentrations of calcium and phosphate, but not in that of magnesium, during the course of pregnancy; calcium concentrations showed a maximal decrease at term. Conclusions: Changes in serum PTHrP during the course of pregnancy, at term and postpartum have been demonstrated, suggesting that the placenta (during pregnancy) and mammary glands (postpartum) are the main sources of PTHrP. No support for the concept of ‘physiological hyperparathyroidism’ of pregnancy could be demonstrated in the present work. The pregnancy-induced increase in calcitriol concentration may thus be the primary mediator of the changes in maternal calcium metabolism, but the involvement of other factors cannot be excluded.

Growth hormone-releasing peptides

Abstract: Growth hormone-releasing peptides (GHRPs) are synthetic, non-natural peptides endowed with potent stimulatory effects on somatotrope secretion in animals and humans. They have no structural homology with GHRH and act via specific receptors present either at the pituitary or the hypothalamic level both in animals and in humans. The GHRP receptor has recently been cloned and, interestingly, it does not show sequence homology with other G-protein-coupled receptors known so far. This evidence strongly suggests the existence of a natural GHRP-like ligand which, however, has not yet been found. The mechanisms underlying the GHRP effect are still unclear. At present, several data favor the hypothesis that GHRPs could act by counteracting somatostatinergic activity both at the pituitary and the hypothalamic level and/or, at least partially, via a GHRH-mediated mechanism. However, the possibility that GHRPs act via an unknown hypothalamic factor (U factor) is still open. GHRP-6 was the first hexapeptide to be extensively studied in humans. More recently, a heptapeptide, GHRP-1, and two other hexapeptides, GHRP-2 and Hexarelin, have been synthesized and are now available for human studies. Moreover, non-peptidyl GHRP mimetics have been developed which act via GHRP receptors and their effects have been clearly demonstrated in animals and in humans in vivo. Among non-peptidyl GHRPs, MK-0677 seems the most interesting molecule. The GH-releasing activity of GHRPs is marked and dose-related after intravenous, subcutaneous, intranasal and even oral administration. The effect of GHRPs is reproducible and undergoes partial desensitization, more during continuous infusion, less during intermittent administration: in fact, prolonged administration of GHRPs increases IGF-1 levels both in animals and in humans. The GH-releasing effect of GHRPs does not depend on sex but undergoes age-related variations. It increases from birth to puberty, persists at a similar level in adulthood and decreases thereafter. By the sixth decade of life, the activity of GHRPs is reduced but it is still marked and higher than that of GHRH. The GH-releasing activity of GHRPs is synergistic with that of GHRH, is not affected by opioid receptor antagonists, such as naloxone, and is only blunted by inhibitory influences, including neurotransmitters, glucose, free fatty acids, gluco corticoids, recombinant human GH and even exogenous somatostatin, which are known to almost abolish the effect of GHRH. GHRPs maintain their GH-releasing effect in somatotrope hypersecretory states such as in acromegaly, anorexia nervosa and hyperthyroidism. On the other hand, their good GH-releasing activity has been shown in some but not in other somatotrope hyposecretory states. In fact, reduced GH responses after GHRP administration have been reported in idiopathic GH deficiency as well as in idiopathic short stature, in obesity and in hypothyroidism, while in patients with pituitary stalk disconnection or Cushing's syndrome the somatotrope responsiveness to GHRPs is almost absent. In short children an increase in height velocity has also been reported during chronic GHRP treatment. Thus, based on their marked GH-releasing effect even after oral administration, GHRPs offer their own clinical usefulness for treatment of some GH hyposecretory states.

Percutaneous ethanol injection therapy in the treatment of thyroid and parathyroid diseases

Abstract: Relevant English language articles published from 1966 to 1995 regarding ethanol therapy in the treatment of thyroid and parathyroid diseases were identified through a MEDLINE search and manual searches of identified articles The sclerosing properties of ethanol have been recognized for many years and have offered interventional possibilities in the management of various benign as well as malignant lesions The mechanism of action of ethanol appears to be related to a direct coagulative necrosis and local partial or complete small vessel thrombosis Ultrasound-guided percutaneous ethanol injection therapy (PEIT) is rapid and performed on an out-patient basis and has now gained wide acceptance due to the accumulating evidence of the efficacy and safety of this therapeutic tool Yet, there is a lack of prospective, randomized clinical trials comparing PEIT with 131 I therapy or surgery with regard to its effects especially long-term ones and it should therefore still be considered an experimental procedure In benign endocrine diseases, PEIT has shown promising results in the treatment of autonomous thyroid nodules, benign solitary cold solid as well as cystic thyroid nodules and parathyroid tumours Its use in pretoxic and toxic thyroid nodules has been evaluated in several uncontrolled studies all demonstrating a high success rate in spite of the large number of treatments needed So far efficacy and cost-effectiveness seem inferior to 131 I and surgery Short-term results of PEIT in benign cystic thyroid nodules are convincing with a high cure rate, but no controlled studies with long-term results are available Preliminary results suggest that PEIT could become an alternative to surgical excision or levothyroxine therapy in the symptomatic solid cold benign thyroid nodule Ultrasound-guided PEIT of parathyroid tumours has proven to be a useful method in highly selected patients in whom surgery has been found non-attractive and medical treatment ineffective However, no prospective randomized trials have been published comparing the results of PEIT in parathyroid tumours with conventional surgical and medical treatments PEIT has never been tested against standard therapy, but seems inferior to 131 I and surgery Side-effects caused by ethanol injection are generally few and transient and are related to the injection into solid nodules rather than cysts Ethanol injection into solid profund nodules may seriously jeopardize subsequent surgery because of perinodular fibrosis As an experimental procedure, not yet evaluated sufficiently, it should be reserved for patients who cannot or will not undergo standard therapy Caution in routine use is advisable

Paracrine regulation of cellular interactions in the testis: factors in search of a function.

Abstract: Throughout evolution, gamete generation and sex hormone production are the two processes combined in the testis. The local proximity of sex steroid-producing cells and spermatogenic cells allows multiple cellular interactions to occur and thereby facilitates the modulation and/or synchronisation of both testicular functions. This mini review provides an introduction to the vast variety of different testicular cell types, the unique bi-compartmental organisation of the testis, the many factors being released in the testis and the different forms of cellular interactions occurring between testicular cells. Selected members of two groups of signal molecules (sex steroids, growth factors) are described in detail and specific examples for the intratesticular actions of signalling factors are presented.

Thyroid hormone and gene expression in the regulation of mitochondrial respiratory function

Abstract: Thyroid hormone has a profound effect on cellular respiration. Abnormally high levels of this hormone accelerate respiration in conjunction with a general increase in metabolism while pathologically low amounts cause low levels of respiration with a general slowing of metabolic activity. The affect on respiration is primarily the result of changes in the expression of respiratory genes and modulation of inner membrane structure. This review focuses on the regulation of respiratory gene expression by thyroid hormone. Respiratory genes are encoded in both the nucleus and the mitochondrion, the products of which are required in stoichiometric amounts for proper assembly of the respiratory chain. Thyroid hormone influences the expression of a number of nuclear encoded respiratory genes at the level of mRNA and enhances expression of mitochondrially encoded respiratory genes. Therefore, thyroid hormone appears to affect gene regulation in two different cell compartments. The current evidence for a direct thyroid hormone/thyroid receptor regulation of these respiratory genes and possible indirect pathway(s) mediating the thyroid effect is discussed.

Long-term vitamin D3 supplementation may have adverse effects on serum lipids during postmenopausal hormone replacement therapy

Abstract: Objective: The positive short-term effects of postmenopausal hormone replacement therapy (HRT) on serum lipids are well known, but it has been suggested that they vanish with time. Cholecalciferol (vitamin D3) is widely used to prevent postmenopausal osteoporosis but the influence of vitamin D3 on serum lipids is poorly known. The long-term effects of HRT and vitamin D3 on the concentrations of serum lipids were studied in a population-based prospective 3-year study. Design and methods: 464 women were randomized into four treatment groups: (i) HRT (sequential combination of 2 mg estradiol valerate and 1 mg cyproterone acetate), (ii) Vit D3 (vitamin D3 300 IU/ day), (iii) HRT+Vit D3 (both as above), (iv) placebo (calcium lactate 500 mg/day). Results: 320 women completed the study. After three years of treatment, serum concentrations of low density lipoprotein (LDL) cholesterol decreased in the HRT group (10.1%, P<0.001) and the HRT+Vit D3 group (5.9%, P=0.005), increased in the Vit D3 group (4.1%, P=0.035) but remained unchanged in the placebo group. The concentrations of total cholesterol decreased by 5.8% in the HRT group (P<0.001) and by 3.3% in the HRT+Vit D3 group (P=0.023), but did not change in the other two groups. Serum concentrations of high density lipoprotein (HDL) cholesterol decreased in the Vit D3 group (5.2%, P=0.001), HRT+Vit D3 group (3.7%, P=0.046), and the placebo group (4.5%, P=0.006) but did not change significantly in the HRT group. The HDL/LDL ratio increased in the HRT group (10.5%, P=0.006) and decreased in the Vit D3 group (10.5%, P<0.001) whereas no changes occurred in the other two groups. In addition, serum triglycerides increased similarly in all groups (14.0‐ 18.8%, P<0.05‐0.001). Conclusions: Our results confirm the positive long-term effect of HRT with sequential estradiol valerate and cyproterone acetate on serum lipid concentrations. In addition, the results suggest that vitamin D3 supplementation may have unfavorable effects on lipids in postmenopausal women. Pure vitamin D3 treatment was associated with increased serum LDL cholesterol. Furthermore, the beneficial effects of HRT on serum LDL cholesterol content were reduced when estradiol valerate was combined with vitamin D3. However, the relevance of these associations to cardiovascular morbidity remains to be established.

Insulin-like growth factor receptors in normal and tumorous adult human adrenocortical glands

Abstract: We have identified and characterized insulin-like growth factor (IGF)-I and IGF-II/mannose-6-phosphate (IGF-II/M6P) receptors in normal adult human adrenocortical tissue. Furthermore, we investigated the IGF-I receptor concentration and binding characteristics in benign and carcinomatous adrenocortical tumors. Membrane preparations of 14 normal adrenocortical glands showed a mean specific 125I-IGF-I binding (SB) of 5.0 +/- 0.5% and a competition by unlabeled ligands which is characteristic of the IGF-I receptor. The Scatchard analysis revealed a single class of high affinity binding sites with a dissociation constant (Kd) of 0.16 +/- 0.03 nmol/l, and a receptor concentration (RC) of 19.2 +/- 2.5 nmol/kg protein. Affinity cross-linking experiments with normal and tumorous adrenocortical tissue displayed a band at an apparent molecular mass of 135 kDa, corresponding to the size of the normal alpha-subunit of the IGF-I receptor. In agreement, 125I-IGF-II binding to normal adult human adrenocortical membranes was characteristic for the IGF-II/M6P receptor, and the Scatchard analysis revealed the presence of a single class of high affinity binding sites (SB 7.5 +/- 0.5%, RC 1137 +/- 265 nmol/kg protein, Kd 2.20 +/- 0.46 nmol/l, n = 6). The identity of the IGF-II/M6P receptor in adrenocortical tissue was further confirmed by Western blotting showing a specific band at 220 kDa. When 125I-IGF-I binding in adrenocortical hyperplasias (SB 4.1 +/- 0.4%, RC 19.6 +/- 2.0 nmol/kg protein, Kd 0.19 +/- 0.04 nmol/l, n = 4) and adenomas (SB 4.0 +/- 1.1%, RC 17.5 +/- 3.1 nmol/kg protein, Kd 0.21 +/- 0.04 nmol/l, n = 4) was compared with the 125I-IGF-I binding in normal adrenocortical tissue, similar IGF-I receptor concentration and binding kinetics were found. In contrast, three out of four hormonally active adrenocortical carcinomas showed a strongly elevated specific 125I-IGF-I binding with a 3- to 4-fold increase in IGF-I receptor concentration, as compared with normal adrenocortical tissue. This resulted in a significantly higher mean specific binding and receptor concentration in adrenocortical carcinomas, while the binding kinetics and the size of the alpha-subunit of the IGF-I receptor remained unaltered (n = 4, SB 13.8 +/- 4.2%, RC 72.2 +/- 21.3 nmol/kg protein, Kd 0.17 +/- 0.02 nmol/l). In summary, we show that intact IGF-I and IGF-II receptors are present in normal adult human adrenocortical tissue. While the abundance of the IGF-I receptor in adrenocortical hyperplasias and adenomas was similar to normal tissue, a strong overexpression of the intact IGF-I receptor was found in three out of four adrenocortical carcinomas.

Greater disorderliness of ACTH and cortisol release accompanies pituitary-dependent Cushing's disease

Abstract: We investigated the episodicity of 24-h ACTH and cortisol secretory profiles in 16 patients with Cushing's disease and 25 healthy matched controls, with a recently introduced scale- and model-independent regularity statistic, approximate entropy (ApEn). The mean (+/-S.E.M.) ApEn value for plasma ACTH concentrations in Cushing's disease was 1.3817 +/- 0.033, and in controls 0.8394 +/- 0.049 (P < 10(-10)); for plasma cortisol concentrations the values were 1.4575 +/- 0.052 and 0.8637 +/- 0.020 respectively (P < 10(-10)), implying greater irregularity of release for both hormones in Cushing's subjects. The calculated sensitivity and specificity of ApEn for ACTH profiles were 94% and 100% respectively. For cortisol the sensitivity and specificity were both 100%. ApEn was not correlated with sex, age, or the total 24-h secretion rate of ACTH and cortisol in patients and controls. The increased ApEn in patients with Cushing's disease points to an increased disorderliness of ACTH and cortisol secretion compared with healthy controls. In conjunction with the available literature, we hypothesize more generally that autonomous endocrine tumors may be typified by reduced regularity, orderliness, or synchrony of the time structure of hormone release.

Lack of effects of circulating thyroid hormone levels on serum leptin concentrations

Abstract: Leptin is the protein product of the ob gene, secreted by adipocytes. It has been suggested that it may play an important role in regulating appetite and energy expenditure. The aim of this study was to evaluate a possible interaction of thyroid hormones with the leptin system. We studied 114 adult patients (65 females and 49 males): 36 were affected with primary hypothyroidism (PH), 38 with central hypothyroidism (CH) and 40 with thyrotoxicosis (TT). Patients with CH were studied both before and after 6 months of L-thyroxine replacement therapy. Body mass index (BMI; kg/m 2 ), thyroid function and fasting serum leptin were assessed in all patients. Since BMI has been proved to be the major influencing variable of circulating leptin levels, data were expressed as standard deviation score (SDS) calculated from 393 male and 561 female controls matched for age and BMI. No difference in SDS was recorded between males and females whatever the levels of circulating thyroid hormones. In males, no significant difference was recorded among the SDSs of PH (π0.366 1.2), TT (π0.3561.2) and CH (0.0161.4) patients. Females with PH had an SDS significantly lower than TT females (π0.7761.0 vs π0.0661.2; P < 0:02), while no significant differences between CH (π0.3460.7) and TT females or between CH and PH females were observed. SDS in CH patients after 6 months of L-thyroxine therapy significantly varied only in females (0.2561.4). In conclusion, circulating thyroid hormones do not appear to play any relevant role in leptin synthesis and secretion. However, as females with either overt hypo- or hyper-thyroidism or central hypothyroidism after L-thyroxine therapy show differences in their SDSs, a subtle interaction between sex steroids and thyroid status in modulating leptin secretion, at least in women, may occur.

Molecular structure of the human gonadotropin-releasing hormone receptor gene

Abstract: GnRH receptors belong to the family of G protein-coupled receptor proteins and have been localized to the anterior pituitary, brain and reproductive organs as well as many steroid-dependent tumor tissues. Recently, cDNAs for the GnRH receptors of several species including the human have been cloned. To determine the structure of the gene encoding the human GnRH receptor, we isolated the receptor gene clones from the human genomic libraries. Comparison of the genomic and cDNA sequences revealed that the human GnRH receptor gene is composed of three exons and two introns and spans over 20 kb in size. Exon 1 encodes the 5 0 untranslated sequence and nucleotide ˛ 1t o ˛522 in the open reading frame, exon 2 encodes nucleotide ˛ 523 to ˛ 742 and exon 3 encodes nucleotide ˛ 743 to ˛ 987 in the open reading frame as well as the 3 0 untranslated sequence. Southern blot analysis of genomic DNA and localization of the GnRH receptor gene to a single site on human chromosome 4 (4q13) indicate the presence of a single copy of the gene in the human genome. Several regulatory sequences for various hormones and other regulatory factors were identified, including PEA-3, AP-1, AP-2, and Pit-1 sites. In addition, glucocorticoid/progesterone response element, thyroid hormone response element, and cAMP response element sequences were identified. Reverse transcriptase-primer extension and 5 0 RACE analysis of the human pituitary RNA demonstrated the presence of multiple transcriptional start sites upstream of the translational start site. Analysis of the 5 0 flanking region of the gene also revealed the presence of multiple TATA and CAAT sequences. The finding of multiple transcriptional start sites raises the possibility of tissue-specific regulation and the existence of variable size transcripts. Chimeras containing 1.26 kb (π534 to 728) of the 5 0 flanking region of the receptor gene and the luciferase (Luc) gene expressed a significant luciferase activity when transfected into a human endometrial tumor cell line (HEC-1A) and a breast tumor cell line (MCF-7) but not in a mouse pituitary gonadotrope cell line (aT3‐1), suggesting the existence of multiple promoter elements in the gene. These findings indicate a multiplicity of regulation of expression of the GnRH receptor and provide the substrate for detailed investigation in the reproductive system.

One microgram is the lowest ACTH dose to cause a maximal cortisol response. There is no diurnal variation of cortisol response to submaximal ACTH stimulation

Abstract: There are many suggestions in the literature that the adrenal gland is more sensitive to ACTH in the evening than in the morning. However, all these studies in humans were conducted when the basal cortisol level was not suppressed, and were based on the observation that, after stimulation, the increases in cortisol differed, though the peak values were the same. To examine this, we established the lowest ACTH dose that caused a maximal cortisol stimulation even when the basal cortisol was suppressed, and used a smaller dose of ACTH for morning and evening stimulation. The lowest ACTH dose to achieve maximal stimulation was found to be 1.0 microgram, with which dose cortisol concentration increased to 607.2 +/- 182 nmol/l, compared with 612.7 +/- 140.8 nmol/l with the 250 micrograms test (P > 0.3). The use of smaller doses of ACTH (0.8 and 0.6 microgram) achieved significantly lower cortisol responses (312 +/- 179.4 and 323 +/- 157.3 nmol/l respectively; both P 0.3 for both times). These results show that 1.0 microgram ACTH, used latterly as a low-dose test, is very potent in stimulating the adrenal, even when baseline cortisol is suppressed; smaller doses cause reduction of this potency. Our data show that there is probably no diurnal variation in the response of the adrenal to ACTH, if one eliminates the influence of the basal cortisol level and uses physiologic rather than superphysiologic stimuli.

Chromogranin A and chromogranin B are sensitive circulating markers for phaeochromocytoma

Abstract: Specific assays for measurements of circulating chromogranin (Cg) A, CgB, CgC and pancreastatin (Ps) have recently been developed. The aim of the present study was to investigate the usefulness of these markers in diagnosing and following the effects of treatment of patients with phaeochromocytoma, and to compare the results with those concerning other biochemical markers. CgA was elevated in 19/21 (90%), CgB in 17/21 (81%), Ps in 9/21 (43%) and neuropeptide Y in 9/21 (43%) of the patients. Urinary noradrenaline was increased in 19/21 (90%) and urinary adrenaline in 17/19 (89%) of the patients. All patients had increased levels of either urinary catecholamines or plasma chromogranins. In one patient levels of CgA, CgB and Ps were measured at frequent intervals before, during and after surgery. The CgA level fell to normal shortly after the tumour was removed, whereas the CgB level decreased towards normal over the course of several days. Significant correlation was observed between the contents of CgA and CgB in the tumour tissue and the plasma levels of CgA and CgB respectively. We conclude that CgA and CgB are sensitive circulating markers for phaeochromocytoma and that measurements of both urinary catecholamines and plasma chromogranins improve the diagnostic sensitivity. Furthermore, measurements of CgA may be useful in assessing the radicality of surgery in the early postoperative period.

Plasma bovine pregnancy-associated glycoprotein concentrations throughout gestation in relationship to fetal number in the cow

Abstract: This study characterized the peripheral plasma bovine pregnancy-associated glycoprotein (bPAG) profile throughout gestation and examined the effect of stage of gestation and fetal number on this profile in Holstein cows after non-surgical embryo transfer. Cows (n o 12) were divided into three groups: group 1 o normal singleton pregnancies (n o 5); group 2 o normal twin pregnancies (n o 5); group 3 o abnormal twin pregnancies (n o 2). Blood was collected about every third day from day 0 (defined as the first day of standing estrus), then daily for the last 10 days of gestation, and sampling was stopped one day postpartum. The time-related changes in plasma bPAG concentrations were significantly (P < 0:01) affected by the stage of gestation and fetal number (P < 0:01), except during the last 10 days of gestation. In both normal pregnancy groups, bPAG concentration increased rapidly during the first trimester (0.560.1 to 14.661.7 ng/ml and 1.060.6 to 21.864.8 ng/ml, in singleton and twin-bearing groups respectively), then progressively between days 160 and 20 prepartum (31.666.2 to 114.3631.3 ng/ml and 41.667.4 to 155.8636.6 ng/ml in singleton and twin-bearing cows respectively). The mean concentration between days 20 and 10 prepartum approximately tripled (P < 0:001) in both these groups of cows (114.3631.1 to 493.0675.3 ng/ml and 155.8636.6 to 409.36114.7 ng/ml in singleton and twin-bearing cows respectively), but between days 10 prepartum and parturition the values increased about threefold (P < 0:01) in the singleton group (493.0675.3 to 1352.86286.5 ng/ml) and fivefold (P < 0:001) in the twin-bearing group (409.36114.7 to 2154.06505.7 ng/ml). The two cows in group 3 that gave birth prematurely to a stillborn calf or to a schistosomus reflexus calf exhibited an aberrant bPAG profile. Our results indicate that peripheral bPAG concentrations are correlated to the stage of gestation and fetal number, and that the profile of the peripheral plasma concentrations provides a useful indication of the feto‐placental status.

Biological activities of thyroid hormone receptors

Abstract: In recent years a large amount of data has been gathered on the biology of thyroid hormone receptors. The receptor proteins have been analyzed from the physiological and structural points of view. Most of the information has been summarized in several recent excellent reviews (1–6). The thyroid hormone receptors (TR) are ligand-modulated transcription factors which are members of a large superfamily that includes nuclear receptors for other small, hydrophobic molecules such as steroids, vitamin D3, retinoic acid, prostaglandins, terpenoids, farnesoids and fatty acids, and also the so-called orphan receptors with no recognizable ligand. They bind triiodothyronine (T3) with an affinity about 10 times higher than thyroxine (T4) and activate or repress gene expression upon ligand binding. In addition, an important property of the thyroid hormone receptors is their ability to influence gene expression in the absence of the hormone. In most cases this is reflected in a repression of the target genes which is relieved upon ligand binding, although there are also examples of ligand-independent stimulation of transcription. Little is known of the biological consequences of this intrinsic receptor property. The repressor activity of mutated T3 receptors that have lost the ability to bind hormone is considered to play a role in the pathogenesis of the thyroid hormone resistance syndromes. Receptor expression during development precedes the onset of fetal thyroid function and, with the reservations imposed by placental transfer of maternal thyroid hormone, the unliganded receptor might influence fetal development through mechanisms that are at present unknown. To shed light on this problem, we and others have analyzed the influence of exogenous T3 receptor expression on the phenotype of cultured cells which express no or little T3 receptors unless engineered to do so. The purpose of this review is to summarize the available data in this direction and to try to formulate an hypothesis concerning receptor function.

Twenty-four-hour rhythms of plasma catecholamines and their relation to cardiovascular parameters in healthy young men

Abstract: Diurnal and ultradian rhythms of plasma norepinephrine and epinephrine and their role in the regulation of cardiovascular parameters were investigated over 24 h of recumbency in a group of five men. Catecholamines were measured at 10 min intervals, and blood pressure and heart rate were recorded continuously. Norepinephrine and epinephrine rapidly fluctuated in each subject, with no obvious diurnal rhythm. Spectral analysis suggested two ultradian rhythms with periods of around 12 h and 50‐100 min for both catecholamines. The pulse detection programs PULSAR and CLUSTER revealed 20‐30 pulses/24 h for norepinephrine and epinephrine, with a significant correlation between the two rhythms (r=0·63‐0.80, P<0·001). Neither the frequency nor the amplitude of these rapid fluctuations differed between day and night. Arousal in the morning caused a small increase in plasma catecholamines and getting out of bed a large increase. Thus changes in posture and activity are the main influences on the diurnal variations of plasma catecholamines reported previously, while the ultradian rhythms of sympathoadrenomedullary activity appear to be of intrinsic origin. Blood pressure and heart rate exhibited a diurnal rhythm with a nightly decrease. Arousal and rising from bed increased blood pressure and heart rate significantly. Although the amplitude of the rapid fluctuations of plasma catecholamines at times exceeded those caused by postural changes in the morning, when both plasma norepinephrine and epinephrine levels correlated highly with all cardiovascular parameters, correlations were not significant during recumbency. Thus the intrinsic ultradian fluctuations of plasma catecholamines appear not to be involved in the control of cardiovascular parameters during recumbency, and the increase in blood pressure and heart rate in the morning appears to be controlled by direct sympathetic neural input to the heart and vasculature in response to changes in activity and posture rather than by an endogenous surge of plasma catecholamines.

True hermaphroditism: clinical aspects and molecular studies in 16 cases.

Abstract: Although true hermaphroditism (TH) accounts for less than 10% of intersex patients, it stands as a diagnostic challenge and has allowed a better understanding of the mechanisms involved in sexual differentiation. In this paper we review the clinical and laboratory data as well as molecular biology findings on 16 TH patients followed up at the Pediatric Endocrine Unit, Instituto da Crianca, Hospital das Clinicas, Sao Paulo University Medical School. They were of a mean age of 3 years 8 months and nine of them were black. All the patients had ambiguous external genitalia as the main complaint. The 46,XX karyotype accounted for 50% of the cases and the ovotestis was the most frequent gonad found (59%). In the eight TH patients with a 46,XX karyotype, the sex-determining region of the Y chromosome (SRY) was negative, posing an intriguing question about the testicular differentiation mechanisms involved in these cases. In 7/19 ovotestes, the ovarian portion of the gonad has been preserved, keeping open the possibility of fertility. The female sex option was made in 10/16 cases (62.5%) and three patients exhibited spontaneous puberty. The mechanism through which testicular tissue develops without SRY has not yet been completely clarified, suggesting the involvement of the X chromosome as well as autosomal genes in the process.

The dog thyroid primary culture system: a model of the regulation of function, growth and differentiation expression by cAMP and other well-defined signaling cascades

Abstract: Provided adequate culture conditions are found, specialized cells may keep in vitro some differentiated functions they are known to exert in the whole organism. These functions are responsive in vitro to purified hormones, neurotransmitters or growth factors normally secreted by other cell types. These factors are, therefore, assumed, but frequently not proved, to produce analogous effects in vivo, thus participating in the homeostasis of the whole organism. In this way, much of the modern understanding of the regulation of a defined cell within the organism relies on a mental reconstitution, which combines bits of experimental information obtained from various artificial culture systems, within a framework of ‘rules’ dictated by well admitted clinical observations and decades of in vivo animal experimentation. In vitro experimental observations that fit these rules are, therefore, called ‘mechanisms’; the others are disregarded as ‘culture artefacts’. This view is of course too simplistic. Transgenic and knockout animals remind us that in vitro and in vivo mechanisms may differ. On the other hand, previously unsuspected functions or regulations demonstrated in culture systems may eventually prove to have important physiological or pathological relevance. However, the correlation between in vivo and in vitro observations requires an in depth knowledge and understanding of the in vitro systems. For the study of thyroid cell differentiated functions and proliferation, various culture systems have been developed, using either primary cultures or immortal cell lines of different species. Both have advantages and disadvantages. The rat FRTL5 cell line is by far the most frequently used system. It retains most of the features of differentiated follicular thyroid cells, such as thyroidstimulating hormone (TSH)-dependence of growth (but also survival), iodide uptake, thyroglobulin (Tg) and thyroperoxidase (TPO) gene expression. However, the immortality of this cell line is sufficient evidence that it has lost some of the basic mechanisms of cell cycle control. In nude mice, FRTL5 cells develop TSHdependent tumors (1). Moreover this system suffers from instability (2) and clonal variability (3, 4) which explains the opposite results sometimes obtained in different laboratories. The FRTL5 cell line has lost the epidermal growth factor (EGF) control of growth (5), and b-adrenergic cAMP regulation (6), which is re-acquired in one of its variants (4). Because of its simplicity and accessibility, because it allows permanent transfections and genetic experiments and also because of the increasing difficulty in obtaining animals for experimentation, FRTL5 is now the preferred and often only used system in the majority of in vitro studies of thyroid biology (over 600 studies, mainly from the United States, Italy and Japan). Perhaps because of a personal bias, we consider that cells that are not selected by long-term in vitro propagation are less remote from physiology. We have thus always been surprised to observe that the relevance for the thyroid gland of observations from thyrocyte primary cultures is often definitively accepted only once they have been confirmed from FRTL5 cells, rather than conversely (we are all guilty of regarding what exists in our own model system as the only truth!). The confrontation of the different thyroid primary culture systems has pointed out the importance of possible species differences, but also the influence of culture conditions, and the fact that cells have a ‘memory’, which means that their characteristics are not fully stabilized and may evolve depending on their previous in vivo and in vitro story. In the last decade, the amount of information collected from the dog thyroid primary culture system has justified it emerging as the ‘challenger’ of the FRTL5 cell line as an in vitro model of thyroid cell biology. The aim of this review is to summarize the characteristics of this system and its contribution to the regulation of thyroid function, cell proliferation and differentiation. Whereas differences between systems are fully recognized (7), this review is not aimed at drawing up their catalog. We hope that the information on the properties of dog thyrocytes in culture assembled here may help other thyroidologists European Journal of Endocrinology (1997) 137 579–598 ISSN 0804-4643

Sex-based differences in serum leptin concentrations from umbilical cord blood at delivery.

Abstract: Sex-based differences in serum leptin concentrations have been reported in adolescence and adulthood. To discover when such differences were generated, serum leptin concentrations were measured in umbilical cord blood from 46 healthy infants and in the mother's blood at delivery. Considering the respective body weights of the mothers and infants (68.5±1.3kg and 3.3±0.0kg). umbilical cord concentrations of leptin were disproportionately high in the infants (9.4 ±1.2 μg/l) compared with those in the mothers (18.7±1.3 μg/l). Them was a wide variation in the infant leptin values (1.2-56.8 μg/l) that did not correlate with height, weight, cephalic circumference, or any other growth-related parameter. The most striking differences emerged when results were analysed by sex: umbilical cord concentrations of leptin in the girls (12.9±2.5 μg/l) were significantly (P<0.01) greater than those in the boys (6.8±0.9 μg/l), although no differences in leptin concentrations were observed between the mothers who gave birth to a girl (19.5±2.2 μg/l) and those who gave birth to a boy (18.1±1.7 μg/l). The sex-based differences were not attributable to any growth-related differences between the sexes, except heavier placental weights in the girls (P<0.007) than in the boys. These differences in leptin concentrations may reflect a sex-based difference in the regulation of leptin production by the fetal adipose tissue.

Dendritic cells and macrophages in the pituitary and the gonads. Evidence for their role in the fine regulation of the reproductive endocrine response

Abstract: Blood monocytes are able to mature into macrophages as well as into dendritic cells, Dendritic cells and macrophages have mainly been studied for their function in the immune response, e.g. in the presentation of antigens to lymphocytes and in the phagocytosis/degradation of unwanted material. The cells are also, however, important producers of a variety of signalling molecules and hormones and are thus involved in other physiological functions such as wound healing, the regulation of the microcirculation and the regulation of the function and growth of endocrine cells, This review summarizes the existing evidence for a regulatory role of dendritic cells and macrophages in the function and growth of hormone-producing cells of the pituitary-gonadal axis. It focusses on the presence, localization and phenotype of dendritic cells and macrophages in the anterior pituitary and the gonads, the endocrine regulatory role of cytokines produced by these cells and the existence of putative feedback mechanisms between endocrine cells of the pituitary-gonadal axis and dendritic cells and macrophages. The recognition of a 'floating endocrine-regulatory force' of monocyte-derived cells that also plays a role in the initiation of immune responses has implications for our understanding of the pathogenesis of gonadal and pituitary autoimmune reactions.

Serum leptin in obesity is related to gender and body fat topography but does not predict successful weight loss.

Abstract: Objective: Leptin is the product of the ob gene shown to regulate body fat and appetite in mice. It is produced by human adipose tissue also, but its physiological functions in man are poorly known. Study design and methods: We studied serum leptin concentrations in ten obese men and 35 obese women (age and body mass index 42 6 7 years and 35:1 6 3:6 kg/m 2 respectively) before (baseline) and at 17 and 57 weeks during weight loss of 10:9% of the initial weight. Results: Serum leptin concentrations at baseline were 55% higher in women than in men (after adjustment for age and body fat mass, P o 0:002) and remained so during the follow-up. At baseline, serum leptin correlated with fat mass (r o 0:60, P < 0:001) estimated by bioelectrical impedance, and the changes in leptin concentrations from baseline to week 17 correlated with the changes in fat mass (r o 0:73, P < 0:001), but baseline leptin levels were not predictive of the successful weight loss. Leptin concentrations correlated with hip circumference (r o 0:49, P < 0:001 at baseline adjusted for age and sex), but the correlation with waist circumference became evident only during the weight loss (at week 57, r o 0:63, P < 0:001). Conclusions: Serum leptin concentrations are higher in obese women than in obese men before and during weight loss, but the topography of fat tissue influences serum leptin concentrations. Serum leptin concentrations do not predict the response to weight reduction.

Widespread transcription of the growth hormone-releasing peptide receptor gene in neuroendocrine human tumors

Abstract: GH-releasing peptides are a new class of potent GH secretagogs (GHS) in vivo and in vitro. In normal man GHS also elicit low but definite ACTH and prolactin secretion. Recently it was shown that patients with pituitary corticotrope adenomas respond to GHS with a dramatic rise in ACTH secretion, and it has been suggested that GHS may provide a diagnostic tool to differentiate Cushing's disease from the ectopic ACTH syndrome. GHS actions are mediated by a G protein-coupled receptor recently characterized and cloned in man and rat. In this study we analyzed GHS receptor (GHS-R) expression in various types of pituitary adenoma and in endocrine and non-endocrine lung tumors by RT-PCR. GHS-R transcription was detected in all normal pituitaries and GH-secreting adenomas as expected. The receptor was also transcribed in some prolactin-secreting adenomas and non-functioning adenomas, and, more strikingly, in all 18 ACTH-secreting pituitary adenomas studied. Furthermore, it was frequently expressed in endocrine bronchial tumors, especially carcinoids, whereas it was not found or barely detectable in non-endocrine bronchial tumors. Again ACTH-secreting carcinoids of the lung were all positive for GHS-R expression. These results show that GHS-R transcription is a common feature of endocrine tumors independent of their type and origin.

Lanreotide in the treatment of patients with thyroid eye disease

Abstract: Octreotide, a potent synthetic somatostatin (SM) analogue, was recently evaluated and found to have a beneficial effect in thyroid eye disease (TED), mostly in those patients with a positive Octreoscan-111. Lanreotide (LRT; Somatuline-Ipsen), a new SM long-acting analogue, is more active than natural SM and shows a much longer duration of action. The aim of the present preliminary study was to evaluate the therapeutic effect of LRT in the treatment of TED. Five patients, three males and two females, mean age 50.6 +/- 7.6 S.D. (45-64) years, all with severe symptoms of TED were studied. A similar number of patients, matched for age, sex and severity of ophthalmopathy served as controls. All the patients and controls were investigated with orbital scintigraphy using 111 In DTPA-D-Phe1-octreotide (Octreoscan-111) and selected on the basis of positive octreoscan. The NOSPECS system, as adapted by Donaldson et al. (Journal of Clinical Endocrinology and Metabolism 1973 37 276-285) and a disease activity score, as proposed recently by an International Workshop, have been followed in this study in order to evaluate the response to treatment. The five patients who comprised the treatment group received 0.04 g LRT i.m. once every 2 weeks over a period of 3 months, after which the Octreoscan-111 was repeated. The control patients were given an injection of water i.m., also once every 2 weeks for 3 months, after which they were evaluated clinically. No Octreoscan-111 was performed in the controls. All patients and controls were evaluated by the same physician, who was unaware of the type of treatment used. A decrease in the NOSPECS score and the clinical activity score was regarded as a positive response, while no change or an increase in the NOSPECS score along with no clinical improvement was regarded as a negative response. After 3 months of treatment with LRT, four patients showed a statistically significant improvement in ophthalmopathy in both eyes and one in one eye. Three of the control patients with TED did not show any change, one showed a minor improvement in one eye and no change in the other and one showed deterioration in both eyes. An interesting finding was that orbital Octreoscan-111 activity was absent in all the patients after LRT treatment. In conclusion, these preliminary results show that LRT has a beneficial effect on patients with TED, and that since it has to be given only once every 2 weeks, it is probably superior to any other form of SM treatment. However, as the number of patients was small, further studies are needed to confirm our results.

Results of somatostatin receptor scintigraphy do not predict pituitary tumor volume- and hormone-response to octreotide therapy and do not correlate with tumor histology

Abstract: The value of somatostatin receptor scintigraphy (SRS) to predict the effect of somatostatin analog therapy on pituitary adenomas is not clear, due to the use of different radiopharmaceuticals (123I-Tyr3-octreotide and 111In-pentetreotide) and the small number of patients in previous studies We used 111In-pentetreotide scintigraphy in 49 patients in order to (i) correlate SRS results with basal tumor volume as well as volume- and hormone-response to 3 months of octreotide therapy (Oct-Tx) (ii) identify tumor remnants after incomplete surgery and (iii) evaluate any correlation with immuno histology Twenty-five patients had a GH-secreting adenoma (GH-A, 15 prior to intended surgery, 10 with persistent/recurrent disease after previous therapy) Twenty-four patients had a clinically non-functioning adenoma (NF-A) For SRS, planar and single photon emission computer tomographic images (SPECT) were recorded 4 h and 24 h post injection SRS grading was as follows: GO, no uptake: G1, uptake comparable to normal pituitary; G2, increased uptake: G3, very intense uptake G2/3 was seen in 8/25 GH-A and in 12/24 NF-A Pretreatment tumor volume (magnetic resonance imaging (MRI) tended to be related to 111In-pentetreotide uptake in GH-A with a tumor visible on MRI (G0/1 (n = 10) vs G2/3 (n = 8): 36 +/- 19 vs 105 +/- 65 cm3 (mean +/- SE), P = 0051), but not in NF-A (G0/1 (n = 12) vs G2/3 (n = 12): 170 +/- 101 vs 143 +/- 36 cm3) SRS did not identify a tumor remnant in the 7 MRI-negative patients with persistent post-operative acromegaly Basal GH (6-h profile) and IGF-1 in GH-A did not correlate with SRS results (G0/1 (n = 17) vs G2/3 (n = 8), GH: 323 +/- 182 vs 293 +/- 74 micrograms/l IGF-I: 851 +/- 80 vs 1038 +/- 153 micrograms/l) During Oct-Tx of GH-A neither tumor shrinkage nor GH suppression was related to SRS results In 6 NF-A classified as gonadotropinomas (by their plasma glycoprotein hormone or alpha-subunit concentrations, basally and/or in response to TRH) 111In-pentetreotide uptake was not different from that of the non-gonadotropin/non-secreting adenomas SRS results were not related to the immunohistological subtype in 22 GH-A (monohormonal mixed somatotrope/lactotrope, plurihormonal) or in 22 NF-A (null-cell adenomas, gonadotropinomas silent hormonal adenomas) We conclude that 111In-pentetreotide SRS reflects tumor volume poorly in GH-A and not at all in NF-A It does not predict the effect of Oct-Tx on the volume of both GH-A and NF-A, nor on the GH concentration in GH-A 111In-pentetreotide SRS is unable to identify post-operative tumor remnants not visible on MRI