bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnosis and radioguided surgery with 111In-pentetreotide in a patient with paraneoplastic Cushing's syndrome due to a bronchial carcinoid
Authors: Mansi L , Rambaldi PF , Panza N , Esposito D , Esposito V , Pastore V
Published: January 2005

In a 28-year-old man with Cushing's syndrome, studies investigating a hypophyseal and/or adrenal origin of the disease, including computed tomography and magnetic resonance imaging, were negative. In agreement with reports showing somatostatin receptors on the cell membrane of ectopically secreting ACTH tumours, scintigraphy was performed after intravenous injection of 111 MBq 111In-pentetreotide (OCT). The radiolabelled OCT scan showed a small focal area of intense uptake at the inferior lobe of the right lung. Subsequent radioguided surgery located and defined a small mass (1.8 x 1.4 x 1.6 cm). The probe pinpointed the mass to the right inferior chest lobe, with a tumour/normal tissue count ratio of 6:1 and tumour/hilar normal lymph node ratio of 12:1, thus permitting the complete excision of the tumour to exclude lymph node and/or parietal involvement. A lung carcinoid was diagnosed at histology. The patient is still alive and disease-free 24 months after surgery. 111In-OCT was found to be useful for localizing the ACTH-secreting tumour and also permitted rapid non-invasive differential diagnosis between an ACTH-secreting pituitary adenoma and malignancy causing ectopic ACTH syndrome. This study also showed the clinical usefulness of radioguided surgery in the treatment of bronchial carcinoid.
Insulin sensitizer YM268 ameliorates insulin resistance by normalizing the decreased content of GLUT4 in adipose tissue of obese Zucker rats
Authors: Shimaya A , Noshiro O , Hirayama R , Yoneta T , Niigata K , Shikama H
Published: January 2005

Genetically obese Zucker rats exhibit mild hyperglycaemia and hyperinsulinaemia suggesting the existence of peripheral insulin resistance. We have examined the effects of YM268, an analogue of thiazolidinedione, on the content and translocation of a glucose transporter (GLUT4) in epididymal adipose tissue in 11-week-old obese and lean Zucker rats. The administration of YM268 at a dose of 10 mg/kg for 2 weeks ameliorated hyperglycaemia, hyperinsulinaemia, and impaired glucose tolerance after glucose load in obese rats. The GLUT4 content per fat pad in obese rats was reduced to 36% of that in lean littermates. Obese rats treated with YM268 increased GLUT4 concentrations in their fat pads from a basal value of 36% up to 191% of the level in lean rats. Furthermore, in adipocytes prepared from obese rats, an increase in the ratio of GLUT4 in plasma membrane to the total amount of GLUT4 (PM-GLUT4 ratio) induced by the submaximal concentration of insulin (0.3 nmol/l) was significantly attenuated compared with that in lean rats. But the maximum effect of insulin (3 nmol/l) was not attenuated. Meanwhile, YM268 had no significant effect on the attenuated PM-GLUT4 ratio in response to insulin in obese rats. These data suggested that one of the mechanisms by which YM268 improved insulin resistance in obese Zucker rats was to normalize the decreased GLUT4 content in the adipose tissue.
Interactions of insulin-like growth factor (IGF)-II and growth hormone in vivo: circulating levels of IGF-I and IGF-binding proteins in transgenic mice
Authors: Blackburn A , Dressendorfer RA , Blum WF , Erhard M , Brem G , Strasburger CJ , Wolf E
Published: January 2005

To study interactions between insulin-like growth factor-II (IGF-II) and growth hormone (GH) in vivo, we crossed hemizygous transgenic mice carrying phosphoenolpyruvate carboxykinase (PEPCK)-IGF-II fusion genes with hemizygous PEPCK-bovine GH (bGH) transgenic mice. Offspring harbouring both transgenes (IB), the IGF-II transgene (I) or the bGH transgene (B), and non-transgenic littermates (C) were obtained. Blood samples were taken before (end of week 12) and after (end of week 14) the mice had received a diet high in protein and low in carbohydrates to stimulate PEPCK promoter-controlled transgene expression. Mean serum GH concentrations of both B and IB mice corresponded to 900 ng/ml and increased more than twofold (P < 0.001) after 1 week of the high-protein diet. GH concentrations in controls and I mice were less than 20 ng/ml. Serum IGF-II concentrations in I and IB mice were three-to fourfold higher than those in C and B mice. Whereas IGF-II concentrations were not changed by the high-protein diet in the last two groups, serum IGF-II increased significantly in I (P < 0.001) and IB mice (P < 0.05). This increase was significantly (P < 0.05) less pronounced in IB than in C and I mice. Circulating IGF-I concentrations were about twofold (P < 0.001) higher in B and IB than in C and I mice, and showed a tendency to be lower in I than in C and in IB than in B mice when animals were maintained on the standard diet. The high-protein diet did not change circulating IGF-I concentrations in controls and B mice, but resulted in a significant reduction of serum IGF-I concentrations in I (P < 0.05) and IB mice (P < 0.001). Consequently, after PEPCK-IGF-II transgene expression was stimulated, serum IGF-I concentrations were significantly (P < 0.05) lower in I than in C and in IB than in B mice. Serum IGF-binding protein (IGFBP)-2 concentrations were significantly (P < 0.05) higher in I mice than in all other groups when mice were maintained on the standard diet, with a tendency to reduced IGFBP-2 concentrations in B mice. After the high-protein diet, serum IGFBP-2 concentrations did not change in C and I mice, but increased by two- to threefold in B and IB mice (P < 0.001). Serum IGFBP-3 concentrations tended to be greater in B and IB than in C and I mice, but these differences were mostly not significant. IGFBP-4 concentrations were significantly (P < 0.001) increased by GH overproduction in B and IB mice. Our data suggest that the reduction in circulating IGF-I concentrations by increased IGF-II is most probably due to the limited serum IGF binding capacity and the short half-life of free IGFs, rather than to a reduction in GH-dependent IGF-I production. Effects of GH overproduction on serum IGFBP-2 concentrations depend on dietary factors and may be both inhibitory and stimulatory.
Unique binding pattern to concanavalin A lectin of glycoprotein hormones alpha-subunit hypersecreted by non-functioning pituitary adenomas
Authors: Asteria C , Persani L , Ferrari M , Beck-Peccoz P
Published: January 2005

This study analyzed the structural differences of the carbohydrate chains of circulating free alpha-submit (alpha-SU) hypersecreted in various non-tumoral (primary hypothyroids, postmenopausal women, patients with chronic uremia, normal fetuses) and tumoral (gut carcinoids, TSH-, GH- and pure alpha-secreting pituitary adenomas) clinical conditions. Carbohydrate structures of free alpha-SU were investigated by means of lectin affinity chromatography using Concanavalin A (Con-A), which allows the separation of free alpha-SU in three different fractions (unbound = UB, weakly bound = WB and firmly bound = FB) depending on the nature and maturation of glycosylated chains. The concentrations of alpha-SU in serum and in Con-A fractions were measured by a sensitive and specific IRMA. Free alpha-SU hypersecreted from postmenopausal women, primary hypothyroids, and patients with chronic uremia showed similar binding patterns to Con-A, the percentage of UB fractions (UB: 44.5 +/- 1.9%, 39.5 +/- 3.8%, 48.2 +/- 5.6% respectively) being higher than both WB and FB fractions (WB: 33.2 +/- 1.4%, 30.7 +/- 4.6%, 28.5 +/- 2.1%; FB: 22.3 +/- 0.7%, 29.8 +/- 6.6%, 23.3 +/- 4.2% respectively). In normal fetuses the amount of UB fraction was very high (UB: 70.7 +/- 5.4%). Free alpha-SU from patients with TSH- and GH-secreting adenomas showed a binding pattern to Con-A significantly different from that observed in postmenopausal women taken as controls, the WB fractions being significantly higher (WB: 56.9 +/- 16.8% and 71 +/- 12.4% respectively, P < 0.001). A typical pattern of elution on Con-A, characterized by a prevalence of immature alpha-SU molecules eluted in the FB fraction, was found in patients with pure alpha-secreting adenomas. This chromatographic behavior was significantly different from that seen in the controls, as well as in other pituitary tumors and in gut carcinoids (FB: 41.8 +/- 5.0%, 22.3 +/- 0.7%, 16.8 +/- 6.6%, 10.6 +/- 2.0% respectively). Moreover, in these latter patients the pattern of free alpha-SU binding was exactly the opposite of that observed in pure alpha-secreting adenomas, with a prevalence of mature alpha-SU molecules (UB: 59.1 +/- 4.4 vs 18.3 +/- 7.2%). In conclusion, our data on Con-A affinity chromatography clearly demonstrate that carbohydrate branching of circulating free alpha-SU varies in patients with pituitary adenomas as compared with patients with gut carcinoids or other non-tumoral conditions. Moreover, the finding of a greater proportion of circulating free alpha-SU forms that firmly bind to Con-A in patients with pure alpha-secreting adenomas, seems to be pathognomonic of non-functioning pituitary adenomas.
Widespread transcription of the growth hormone-releasing peptide receptor gene in neuroendocrine human tumors
Authors: de Keyzer Y , Lenne F , Bertagna X
Published: January 2005

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.
Toxic thyroid adenoma: absence of DNA mutations of the TSH receptor and Gs alpha
Authors: Pinducciu C , Borgonovo G , Arezzo A , Torre GC , Giordano G , Cordera R
Published: January 2005

DNA point mutations of the TSH receptor and of the alpha subunit of the stimulatory GTP-binding protein (Gs alpha) have been suggested as major causes of hyperfunctioning thyroid adenomas. However, significant differences in the prevalence of these mutations (from 0.3 to 84%) have been found in different populations. The present study was designed to evaluate further the presence of mutations in discrete fragments of cDNA encoding critical regions of the TSH receptor and of the Gs alpha involved in signal transduction and cAMP production. Genomic DNA extracted from 15 thyroid adenomas and surrounding quiescent thyroid tissues was used as a template to amplify four DNA fragments of TSH receptor and one DNA fragment of Gs alpha. TSH receptor and Gs alpha DNAs were analyzed by a number of techniques. We did not detect any mutations (new or previously described) in our patients. These results confirm that the causes of solitary toxic adenomas are protean, and only some of them may be somatic DNA point mutations. Since the clinical features of solitary toxic adenoma are homogeneous, it could be important to establish the specific molecular defect underlying each case, in order to follow up the patients and to assess their clinical evolution.
Role of conventional ultrasonography and color flow-doppler sonography in predicting malignancy in 'cold' thyroid nodules
Authors: Rago T , Vitti P , Chiovato L , Mazzeo S , De Liperi A , Miccoli P , Viacava P , Bogazzi F , Martino E , Pinchera A
Published: January 2005

The aim of the present study was to establish the usefulness of conventional thyroid ultrasonography (US) and color flow-doppler (CFD) sonography in the assessment of 'cold' thyroid nodules. One hundred and four consecutive patients with thyroid nodules who were to undergo surgery were examined by US and CFD before thyroidectomy. Conventional US evaluated the presence of a halo sign, hypoechogenicity and microcalcifications. The vascular pattern on CFD was classified as follows: Type I, absence of blood flow; Type II, perinodular blood flow; Type III, marked intranodular blood flow. On histology, 30 nodules were diagnosed as malignant (carcinoma, CA) and 74 as benign nodules (BN). On US, the echographic pattern most predictive for malignancy was absent halo sign, which was found in 20/30 CA and in 17/72 BN (P = 0.0001; specificity 77.0%; sensitivity 66.6%). The most specific combination on US, absent halo sign/microcalcifications, was found in 8/30 CA and in 5/74 BN (P < 0.005; specificity 93.2%, sensitivity 26.6%). The Type III pattern on CFD was found in 20/30 CA and 38/74 BN (not statistically significant). The combination of absent halo sign on US with Type III pattern on CFD was found in 15/30 CA and in 8/74 BN (P < 0.0001; specificity 89.0%, sensitivity 50.0%). The combination of absent halo sign/microcalcifications on US with Type III pattern on CFD was the most specific combination of the two techniques, being found in 5/30 CA and in only 2/74 BN (P < 0.01; specificity 97.2%, sensitivity 16.6%). In conclusion, findings on US and CFD become highly predictive for malignancy only when multiple signs are simultaneously present in a thyroid nodule. Thus the predictive value of these techniques increases at the expense of their sensitivity. Only in a small proportion of patients with thyroid carcinoma is US and CFD information highly predictive of malignancy.
Increased transforming growth factor-beta1 plasma concentration is associated with high plasma 3,3',5'-tri-iodothyronine in elderly patients with nonthyroidal illnesses
Authors: Corica F , Allegra A , Corsonello A , Buemi M , Rubino F , Bonanzinga S , Ruello A , Ceruso D
Published: January 2005

OBJECTIVE: To study transforming growth factor-beta1 (TGF-beta1) plasma concentrations in elderly patients with nonthyroidal illnesses (NTI). DESIGN: Case-control study. METHODS: We measured plasma concentrations of tri-iodothyronine (T3), reverse T3 (rT3), thyroxine (T4), free T3 (fT3) and free T4 (fT4) estimates, TSH, and TGF-beta1 in 48 elderly NTI patients consecutively admitted in our Division of Internal Medicine and Metabolic Diseases, and in 11 healthy age- and sex-matched controls. RESULTS: The data on thyroid hormones enabled us to identify three groups: Group A, subjects (8 patients) with T3 and fT3 levels comparable to those in controls: Group B, subjects (30 patients) with T3 and fT3 levels lower than controls but rT3 levels comparable to those of controls; Group C, subjects (10 patients) with T3 and fT3 levels lower than those of controls and higher rT3 levels. The patients of Group C showed higher plasma levels of TGF-beta1 compared with controls. Moreover, we found a positive correlation between TGF-beta1 and rT3 (rs = 0.38, P < 0.01) in the whole group of NTI patients. CONCLUSIONS: Our data seem to confirm the hypothesis that TGF-beta1 could play a role in the pathogenesis of some modifications of thyroid function observed in patients with nonthyroidal illnesses.
Effects of testosterone replacement therapy on cortical and trabecular bone mineral density, vertebral body area and paraspinal muscle area in hypogonadal men
Authors: Leifke E , Korner HC , Link TM , Behre HM , Peters PE , Nieschlag E
Published: January 2005

Loss of bone and muscle mass are major findings of male hypogonadism. In order to determine the long-term effect of testosterone replacement therapy on spinal bone and muscles, the trabecular and cortical bone mineral density, vertebral body area and paraspinal muscle area were assessed by quantitative computed tomography in 32 testosterone-substituted patients, aged 18-74 years, with idiopathic hypogonadotropic hypogonadism (n=6), pituitary insufficiency (n=5), Klinefelter syndrome (n=12) or other forms of primary hypogonadism (n=9). They were followed for a mean period of 3.2+/-1.7 years (mean+/-S.D.), ranging from 1 to 7 years. A significant correlation between initial serum testosterone levels and bone mineral density was found in patients with congenital forms (r=0.58; P<0.05) but not in those with acquired forms. A significant increase in trabecular and cortical bone mineral density (P<0.001) was documented in the course of replacement therapy in all patients regardless of the type of hypogonadism and age of patients. A slight but significant increase in paraspinal muscle area was observed if all patients were taken together (P<0.01). The area of paraspinal muscle correlated with body weight (r=0.58; P<0.001) and moderately with trabecular bone mineral density (r=0.4; P<0.01). Its increase did not correspond to the change observed for trabecular and cortical bone mineral density. Vertebral body area did not change over time. It correlated only with height and weight but not with bone mineral density. In conclusion, testosterone therapy of hypogonadal men improves both trabecular and cortical bone mineral density of the spine independently of age and type of hypogonadism while vertebral area remains unchanged. The effects seen on paraspinal muscles emphasize the clinical benefit of adequate replacement therapy for the physical fitness of hypogonadal men.
Analysis of the relationship between fasting serum uric acid and the insulin sensitivity index in a population-based sample of 380 young healthy Caucasians
Authors: Clausen JO , Borch-Johnsen K , Ibsen H , Pedersen O
Published: January 2005

AIM: To determine whether fasting serum uric acid is associated with the insulin sensitivity index or with other anthropometric, metabolic or environmental features of the insulin resistance syndrome in a population-based sample of young healthy Caucasians. METHODS: The protocol included 380 unrelated Caucasian subjects (age 18-32 years) who had their insulin sensitivity index and glucose effectiveness measured during a combined intravenous glucose (0.3 g/kg body weight) and tolbutamide (3 mg/kg body weight) tolerance test. A number of anthropometric and biochemical tests, including the level of fasting serum uric acid, were carried out. RESULTS: In univariate analyses the concentration of fasting serum uric acid was negatively correlated to the insulin sensitivity index in both men (r2 = -0.25, P = 0.001) and women (r2 = -0.25, P < 0.001). In multivariate analysis controlling for age, gender, body mass index, waist to hip ratio, maximal aerobic capacity, fasting serum triglyceride and creatinine, daily intake of alcohol, smoking, use of oral contraceptives, and disposition for non-insulin dependent diabetes mellitus, the insulin sensitivity index was not significantly associated with fasting serum uric acid. However, 51% of the variation in the fasting serum uric acid level could be explained, and fasting serum triglyceride was the most important determinant of fasting serum uric acid. CONCLUSION: The major determinant of the fasting serum uric acid level in young healthy Caucasians is the fasting concentration of serum triglyceride, which has been shown to be a biochemical feature of the insulin resistance syndrome. Thus, hyperuricaemia appears to be an indirect part of the insulin resistance syndrome through its association with fasting hypertriglyceridaemia.
Changes in the glycosylation pattern of circulating gonadotropins after acute administration of gonadotropin-releasing hormone in patients with anorexia nervosa
Authors: Savastano S , Tommaselli AP , Valentino R , Luciano A , Gigante M , Randazzo G , Contaldo F , Scalfi L , Lombardi G
Published: January 2005

To study the involvement of gonadotropin-releasing hormone (GnRH) in glycosylation of circulating gonadotropin isoforms in anorexia nervosa (AN), 14 amenorrhoic patients with AN, 14 age-matched volunteers in early follicular phase, and five normal-weight re-fed patients with AN were investigated under baseline conditions and after acute administration of GnRH. Plasma gonadotropins were assayed using IRMA before and after concanavalin A affinity chromatography. Baseline plasma gonadotropin levels were lower for both AN and re-fed AN patients than in controls (P<0.005). The increase in FSH and LH after GnRH administration was lower than in controls for AN (P<0.005) and re-fed AN (P<0.005 and P<0.05 respectively) patients. Percentages of total gonadotropin not bound to concanavalin A (complex carbohydrate chains) under baseline conditions were higher in patients with AN than in controls (P<0.005) but decreased after GnRH administration (P<0.001). In re-fed AN patients, the percentage of unbound FSH was higher than in controls (P<0.05), and decreased after GnRH administration (P<0.001), whereas the percentages of unbound LH were not significantly different from controls either before or after GnRH administration. These data suggest that: (a) the acute administration of GnRH induces quantitative and qualitative changes in circulating gonadotropin isoforms in both normal controls and AN patients; (b) during recovery the LH response in re-fed AN patients is associated with a glycosylation pattern that is the same as that for controls.
Asymptomatic 'big' hyperprolactinemia in two men with pituitary adenomas
Authors: Tritos NA , Guay AT , Malarkey WB
Published: January 2005

'Big' and 'big-big' hyperprolactinemia, the presence of increased serum concentrations of high molecular weight (50-60 and 150 kDa respectively) prolactin forms, has mostly been reported in women with idiopathic hyperprolactinemia and normal hypothalamic-pituitary ovarian axis function. It has been suggested that both 'big' and 'big-big' prolactin species are biologically less active than the 22 kDa form predominating in normal individuals. We report the cases of two men with pituitary adenomas who were secreting significant amounts of 'big' (50-60 kDa) prolactin documented by Sephadex G-100 column chromatography. Both patients reported normal sexual function despite high prolactin levels. Results of nocturnal rigidity and tumescence testing were normal, confirming that significant hyperprolactinemia was not interfering with either patient's sexual function. 'Big' hyperprolactinemia should thus be suspected even in male patients with prolactin-secreting pituitary adenomas who maintain adequate sexual function in the presence of high prolactin levels.
Integrins in thyroid tissue: upregulation of alpha2beta1 in anaplastic thyroid carcinoma
Authors: Dahlman T , Grimelius L , Wallin G , Rubin K , Westermark K
Published: January 2005

OBJECTIVE: To evaluate the integrin pattern in the normal thyroid gland and in different pathological disorders including malignant tumors, because the aggressiveness of several malignant tumors correlates with alterations in the expression of one or more integrins. DESIGN: We examined the expression of integrins and E-cadherin immunohistochemically in a large and well-defined sample of normal and pathological human thyroid tissue. METHODS: Cryosections of 58 thyroid tissue specimens from normal tissue, thyrotoxicosis, nodular goiter, oxyphilic adenoma, follicular adenoma, follicular carcinoma, papillary carcinoma and anaplastic carcinoma, and three lymph node metastases were investigated immunohistochemically using monoclonal antibodies specifically recognizing the integrin beta1-, beta4-, alpha1-, alpha2-, alpha3-, alpha5- and alpha6-subunits, or E-cadherin. RESULTS: All thyroid epithelial cells expressed integrin beta1- and alpha3-subunits. Immunostaining of the beta4-subunit and the alpha6-subunits was found only in tumors. The staining pattern in the three lymph node metastases from papillary carcinomas did not differ from that in their primaries. Anaplastic carcinomas demonstrated neoexpression of the integrin alpha2-subunit. E-cadherin was detected in all tissues except anaplastic carcinomas. CONCLUSIONS: Neoexpression of alpha6beta4 was seen in most malignant tumors, whereas alpha2 was exclusively found in anaplastic carcinomas. In the latter, a loss of E-cadherin expression was also seen. These changes in cell adhesion molecule expression strongly suggest an association with the acquisition of proliferative and invasive properties.
Maternal thyroxine and 3,5,3'-tri-iodothyronine kinetics in near-term pregnant rats at two different levels of hypothyroidism
Authors: Versloot PM , van der Heide D , Schroder-van der Elst JP , Boogerd L
Published: January 2005

Thyroid hormones are extremely important for development of the fetal central nervous system. Thyroidectomy results in severe hypothyroidism. In this study two levels of maternal hypothyroidism were reached by administration of different amounts of thyroxine (T4) and 3,5,3'-tri-iodothyronine (T3) to thyroidectomized pregnant rats. We examined the production, distribution and transport of T4 and T3 by performing a kinetic experiment (three-compartment analysis) with intact and thyroidectomized near-term pregnant rats which received either very low (Tx + lowTH) or normal (Tx + TH) doses of T4 and T3. Despite administration of normal doses of thyroid hormones, plasma TSH was still elevated in the Tx + TH rats, meaning that these rats were still mildly hypothyroid. The Tx + lowTH rats were markedly hypothyroid, the plasma T4 and T3 levels being very low. In the mildly hypothyroid rats the transport of T4 from plasma to the fast pool and vice versa was decreased compared with intact near-term pregnant rats. This could imply that much less T4 is transported to the feto-placental compartment. Liver type I deiodinase was decreased, resulting in lowered plasma T3 values. In the markedly hypothyroid rats all pools and rates of transport of T4 and T3 were greatly decreased. In conclusion, even mild hypothyroidism, despite normal plasma T4 values, results in significant changes, especially in maternal T4 transport. We suggest that even mild maternal hypothyroidism will have a negative effect on the availability of maternal T4 for fetuses.
Responsiveness of urinary markers of bone resorption to orchiectomy and clodronate treatment in mature rats: a comparative study
Authors: Rubinacci A , Villa I , Sibilia V , Netti C , Moro G , Pecile A
Published: January 2005

OBJECTIVE: The aim of this study was to assess the responsiveness of two classes of bone resorption markers to the enhancement of osteoclastic activity induced by orchiectomy and to its inhibition by clodronate treatment in mature rats. DESIGN: Bone mineral density (BMD) at femural metaphysis, femural diaphysis, lumbar vertebrae, and the urinary excretion of pyridinoline (Pyr), deoxypyridinoline (D-Pyr), galactosylhydroxylysine (GHyl) and glucosylgalactosylhydroxylysine (GGHyl) were monitored at regular intervals for 30 days prior to and for 60 days following orchiectomy in eleven rats, divided into two groups: five rats untreated and the other six treated with clodronate. RESULTS: Prior to orchiectomy, a significant (P < 0.01) decrease in BMD was observed only at the distal femural metaphysis. This decrease appeared to be associated with a time-dependent increase in the urinary excretion of all markers. Following orchiectomy, the BMD of the untreated group decreased significantly (P < 0.01) at all bone sites. The bone loss was accompanied by a significant (P < 0.01) increase in Pyr and D-Pyr concentrations in urine, whereas urinary GHyl and GGHyl did not change significantly. In the clodronate-treated group, the BMD of the three skeletal sites did not change significantly, while the urinary excretion of all urinary biochemical markers decreased significantly (P < 0.001). CONCLUSION: This study showed that pyridinolines are able to monitor the bone response to orchiectomy and to clodronate treatment response in androgen-deficient mature male rat. whereas glycosides appear prone to confounding factors.
Evaluation of markers of bone and collagen turnover in patients with active and preclinical Cushing's syndrome and in patients with adrenal incidentaloma
Authors: Sartorio A , Conti A , Ferrero S , Giambona S , Re T , Passini E , Ambrosi B
Published: January 2005

Although steroid-induced negative effects on bone and collagen have been well described in corticosteroid-treated patients, few studies have extensively evaluated bone and collagen turnover in patients with endogenous Cushing's syndrome. In this work serum bone-Gla protein (BGP), C-terminal cross-linked telopeptide of type I collagen (ICTP) and N-terminal propeptide of type III procollagen (PIIINP) levels were determined in patients with active (n = 12) and preclinical (n = 6) Cushing's syndrome, adrenal incidentalomas (n = 35) and in healthy controls (n = 28). In patients with overt Cushing's syndrome, serum BGP (0.9+/-0.2 ng/ml), ICTP (2.7+/-0.2 ng/ml) and PIIINP (1.9+/-0.2 ng/ml) levels were significantly lower (P < 0.0001) than in controls (5.5+/-0.2, 3.9+/-0.2 and 3.2+/-0.2 ng/ml respectively). In preclinical Cushing's syndrome, serum BGP (2.5+/-0.8 ng/ml), ICTP (2.2+/-0.1 ng/ml) and PIIINP (2.2+/-0.2 ng/ml) levels were significantly lower than in normal subjects (P < 0.0001, P < 0.0001 and P < 0.02 respectively), being similar to those recorded in overt Cushing's syndrome. In patients with adrenal incidentaloma, serum BGP (4.2+/-0.5 ng/ml) and ICTP (2.9+/-0.2 ng/ml) levels were significantly lower than those found in controls (P < 0.05 and P < 0.001 respectively), while serum PIIINP levels (3.6+/-0.2 ng/ml) did not differ from those of normals. In particular, 9/35 patients with adrenal incidentaloma had markedly depressed BGP levels (<2.0 ng/ml; mean 0.8+/-0.1 ng/ml): all patients of this subgroup showed an exaggerated 17-hydroxyprogesterone increase after ACTH administration. In the same patients, serum ICTP (3.0+/-0.4 ng/ml) and PIIINP (3.6+/-0.2 ng/ml) levels did not differ from those found in the incidentaloma group. In conclusion, our study indicates that bone and collagen turnover are markedly affected in patients with overt and preclinical Cushing's syndrome. Although patients with adrenal incidentaloma do not show any signs or symptoms of overt hypercortisolism, the presence of reduced BGP and ICTP levels might be considered a further index of an 'abnormal' pattern of steroid secretion in some of them. As a consequence, the presence of early alterations in markers of bone turnover might be useful for selecting those patients who need more accurate follow-up of the adrenal mass.
Reduced disorderliness of growth hormone release in biochemically inactive acromegaly after pituitary surgery
Authors: van den Berg G , Pincus SM , Frolich M , Veldhuis JD , Roelfsema F
Published: January 2005

The episodicity of 24 h GH release was studied in 18 patients with active acromegaly, 12 patients 7-10 days after pituitary surgery, 14 patients long after operation (3-17 years), and 21 healthy gender- and age-matched control subjects, using a recently introduced scale- and model-independent regularity statistic, approximate entropy (ApEn). Blood samples were taken at 10-min intervals for 24 h, and plasma GH concentrations were measured by immunofluorometric assay (detection limit 11.5 ng/l). For this study we selected operated patients who were biochemically in remission, defined by normal circulating IGF-I and insulin-like growth factor-binding protein-3 (IGFBP-3) concentrations, normal glucose-suppressed plasma GH concentration (<0.38 microg/l), and the normalization of the paradoxical rise of GH to TRH or GnRH. In patients with active acromegaly ApEn was 1.23+/-0.04, with no overlap with the control subjects (P = 1.2 x 10[-16]), who had an ApEn of 0.40+/-0.04. ApEn in patients shortly after surgery was 0.71+/-0.09 (P < 0.001 vs controls), and long after surgery 0.56+/-0.05 (P < 0.011 vs controls). ApEn values in treated and untreated patients correlated significantly with the plasma concentration of IGF-I (r=0.531) and IGFBP-3 (r=0.598), and the log-transformed 24h GH secretion rate (r=0.749). Shortly after surgery only one-third of the patients had a normal ApEn value, whereas long after surgery about 70% of the patients had a normal ApEn value. Although ApEn eventually normalized in about 70% of the operated patients, the cause of the persistence of abnormal GH release in the remainder of the subjects is not known, and might reflect permanent hypothalamic-pituitary dysfunction or a very early recurrence of the somatotroph adenoma.
Pituitary function in children with hydrocephalus before and after the first shunting operation
Authors: Lopponen T , Saukkonen AL , Serlo W , Tapanainen P , Ruokonen A , Lanning P , Knip M
Published: January 2005

OBJECTIVE: Children with shunted hydrocephalus experience slow linear growth in prepuberty, accelerated pubertal maturation and a reduced final height. A substantial proportion of these patients have a poor growth hormone (GH) response to stimulation and reduced pituitary volume. The basic mechanisms behind these phenomena are still unknown, but one can hypothesize that an unphysiological intracranial pressure (ICP) may be involved. This study was undertaken to investigate the effect of increased ICP on pituitary function. DESIGN: Twenty-one children (nine males) aged 4 months to 15 years were evaluated for pituitary function before and after their first shunting operation. METHODS: A clinical examination was performed, bone age was determined and a combined pituitary stimulation test was performed to evaluate GH, luteinizing hormone, follicle-stimulating hormone, cortisol, thyrotropin and prolactin secretion. RESULTS: GH concentrations were significantly higher 10 and 15 min before the operation (P=0.04 and P=0.03 respectively) than after it. The basal levels of insulin-like growth factor-I (IGF-I) tended to be higher before the operation than afterwards and those of its binding protein-3 (IGFBP-3) were significantly so (P<0.01). CONCLUSIONS: The higher GH response to GH releasing hormone and circulating IGFBP-3 levels in children with hydrocephalus before compared with after their first shunting operation raise the possibility that the reduced GH secretion and retarded linear growth observed in children with shunted hydrocephalus may be a consequence of decreased ICP and/or the lack of physiological pressure variations.
Effect of insulin-like growth factor-I treatment on serum androgens and testicular and penile size in males with Laron syndrome (primary growth hormone resistance)
Authors: Laron Z , Klinger B
Published: January 2005

Serum gonadotrophins. androgens, insulin and insulin-like growth factor-I (IGF-I) were determined before and during long-term treatment with recombinant IGF-I of seven males with Laron syndrome, and the changes correlated with changes in testicular volume and penile size. The subjects were four boys below the age of 5, two boys aged 10 and 14 but prepubertal and one 28-year-old fully sexually developed adult. IGF-I was administered by a once daily subcutaneous injection of 150 microg/kg per day to the boys and 120 microg/kg per day to the adult patient. In the very young boys no change in serum gonadotrophins, androgens, gonads or genitals was registered. In the two older boys and the adult patient, there was a progressive rise in luteinizing hormone, follicle-stimulating hormone and testosterone. Concomitantly, there was an increase in size of the testes and penile length. The two boys started puberty. As very high serum IGF-I levels were registered in the adult patient, the daily dose was progressively decreased to 70 microg/kg per day. Stopping the IGF-I administration in this patient, according to the protocol, led to a return to pretreatment serum levels and testicular and penile size. This report shows for the first time a direct effect of IGF-I on sex hormones and sex organs in the male.
Circulating endothelin-3 and prolactin concentrations in healthy lactating women during the early puerperium
Authors: Malamitsi-Puchner A , Messinis IE , Sakellariou V , Economou E , Michalas S
Published: January 2005

OBJECTIVE: To study the association between the circulating concentrations of endothelin-3 and prolactin in the early puerperium. DESIGN: Prospective clinical study, including twenty-five healthy puerperal women breast-feeding their healthy full-term infants. METHODS: Venous blood was drawn on day 1 and 4 post partum, and plasma endothelin-3 and serum prolactin were determined. RESULTS: Circulating endothelin-3 and prolactin levels on day 4 did not differ significantly from the corresponding levels on day 1. However, a significant negative correlation was found on day 4 between endothelin-3 and prolactin values (r = -0.688, P < 0.001) and an even stronger negative association existed between the net change in endothelin-3 from days 1 to 4 and the corresponding change in prolactin values (r = -0.732, P < 0.001). CONCLUSIONS: On the fourth day post partum, lactating healthy women show negative correlation between circulating endothelin-3 and prolactin levels. Whether this indicates a role for endothelin-3 in the control of prolactin secretion in the post partum period remains to be clarified.
Effect of endotoxin on the hypothalamic-pituitary-adrenal axis in sheep
Authors: Dadoun F , Guillaume V , Sauze N , Farisse J , Velut JG , Orsoni JC , Gaillard R , Oliver C
Published: January 2005

Endotoxin has been shown to stimulate ACTH and cortisol secretion through an action at the hypothalamic level. However, the nature of hypothalamic neurohormones, corticotropin-releasing hormone (CRH) and especially arginine vasopressin (AVP), involved in that regulation is still controversial. The purpose of this study was to determine the effects of an acute i.v. endotoxin administration on CRH and AVP secretion into hypophysial portal blood (HPB). The experiment has been performed in sheep since it is possible to collect HPB and quantify CRH and AVP secretion in this animal under physiological conditions. The release of both peptides into HPB was stimulated by endotoxin injection, the increase in portal AVP being more pronounced than that of CRH. An initial, transient, increase in jugular AVP concentrations was observed, probably due to the activation of magnocellular AVP neurons. In conclusion, our data indicate that the activation of the pituitary-adrenal axis after endotoxin injection is associated with an increased release of both CRH and AVP into HPB. Magnocellular AVP neurons are initially stimulated while parvocellular CRH and AVP neurons are stimulated throughout the experiment.
The endogenous feeding suppressant, 2-buten-4-olide, impairs the pulsatile secretion of luteinizing hormone through endogenous opioid peptides
Authors: Kaji H , Saito S , Shitsukawa K , Irahara M , Aono T
Published: January 2005

OBJECTIVE: To clarify the mechanism of the suppressive effect of 2-buten-4-olide (2-B4O), an endogenous feeding suppressant, on the pulsatile secretion of luteinizing hormone (LH), by studying whether endogenous opioid peptides are involved in this suppressive effect. METHODS: Using ovariectomized (ovx) rats, blood samples were taken every 6 min for 2 h after administration of 2-B4O or saline into the third cerebroventricle (3V) and sequential i.v. injection of naloxone (0. 5 mg/kg per h) or saline. Rats were divided into three experimental groups: group 1: 3V saline + i.v. saline (control); group 2: 3V 2-B4O + i.v. saline; group 3: 3V 2-B4O + i.v. naloxone. Serum LH concentrations were determined by double-antibody RIA. To determine whether 2-B4O affected the biosynthetic activity of the opioidergic neurons within the ovx rat arcuate nucleus, we measured the concentrations of pro-opiomelanocortin (POMC) mRNA, a precursor of beta-endorphin, in the rostral arcuate nucleus using non-radioactive in situ hybridization and a computerized image-analysis system. RESULTS: 2-B4O significantly suppressed the pulse frequency of LH (group 2: 1.5+/-0.33 pulses/2 h, group 1: 2.43+/-0.2 pulses/2 h; P < 0.05), but naloxone blocked its suppressive effect and restored the pulse frequency (group 3: 3.29+/-0.36 pulses/2 h, group 2: 1.5+/-0.33 pulses/2 h: P < 0.01). There were no significant changes in the mean LH concentrations and amplitude. Furthermore, 2-B4O significantly stimulated the expression of POMC mRNA in the rostral arcuate nucleus. CONCLUSION: These results suggest that 2-B4O may impair the pulsatile secretion of LH by activating the opioid pathway within the hypothalamus.
Possible participation of prostaglandins generated in the anteroventral third ventricular region in the hypovolemia-induced vasopressin secretion of conscious rats
Authors: Yamaguchi K , Hama H , Watanabe K
Published: January 2005

OBJECTIVE: The aim of this study was to investigate the roles of prostaglandins (PGs) in the anteroventral third ventricular region (AV 3V), a cerebral site for cardiovascular homeostasis, in hypovolemia-induced vasopressin (AVP) secretion. METHODS: We infused meclofenamate (78. 3 nmol in 1 microl), a PG synthesis inhibitor, or PGE2 (7.1 nmol in 0.5 microl) into the AV 3V of conscious rats, examining their effects on plasma AVP and other variables in the presence or absence of hemorrhages. The hemorrhages (about 14% of blood volume) were conducted successively by taking femoral arterial blood over a 30-s period at 10-min intervals. RESULTS: The first hemorrhage increased plasma AVP in blood samples obtained 10 min later, without affecting plasma angiotensin II (ANG II), arterial pressure and heart rate. The second hemorrhage after 10 min raised plasma AVP further and, remarkably, augmented plasma ANG II, and reduced arterial pressure. The AVP responses to both the first and second hemorrhages were attenuated by meclofenamate infusion into the AV 3V performed 35 min before the first hemorrhage. The meclofenamate infusion did not alter the response of ANG II, while that of arterial pressure was potentiated and heart rate was decreased after the second hemorrhage. These effects of meclofenamate on plasma AVP and the cardiovascular parameters were not found when the drug was infused into the nucleus accumbens, the region slightly distant from the AV 3V, or the lateral cerebral ventricle. In the normovolemic state, meclofenamate administered into the three brain regions did not affect any of the variables monitored. In contrast, application of PGE2 into the AV 3V enhanced plasma AVP, heart rate and arterial pressure after 5 and 15 min. Histological examination indicated that infusion sites of meclofenamate in the AV 3V were close to those of PGE2 in several cases and included areas such as the organum vasculosum of the lamina terminalis, periventricular hypothalamic nucleus, and the median and medial preoptic nuclei. CONCLUSION: These results suggest that PGs synthesized in and/or near the AV 3V may be involved in the regulation of AVP release and cardiovascular function in the hypovolemic state.
Anionic iodotyrosine residues are required for iodothyronine synthesis
Authors: de Vijlder JJ , den Hartog MT
Published: January 2005

Biosynthesis of iodothyronines in thyroglobulin occurs by oxidative coupling of two iodotyrosine residues catalyzed by thyroperoxidase. To study the mechanism of iodothyronine formation, iodine-free thyroglobulin was non-enzymatically iodinated and after removal of non-incorporated iodide, incubated with lactoperoxidase and glucose oxidase between pH 4 and 9. The amount of thyroxine (T4). 3,5,3'-tri-iodothyronine (T3), 3,3',5'-tri-iodothyronine (rT3) and 3,3'-di-iodothyronine (T2) formed was measured by radioimmunoassays after hydrolysis of thyroglobulin. T4 is synthesized out of two di-iodotyrosine (DIT) residues in thyroglobulin. The pH dependence of T4 formation fits the dissociation curve of the DIT phenoxy group (pKa 6.5). The formation of T2, synthesized out of two mono-iodotyrosine (MIT) residues, shows a quite different pH dependence. Below pH 6, T2 synthesis could not be observed, while above pH 7.4 a relatively large increase occurred. The values up to pH 8 fitted the dissociation curve of the MIT-phenoxy group with a pKa of 8.7. The gradual loss in enzymatic activity of peroxidase and oxidase in the reaction made the values obtained above pH 8 unreliable. The importance of the ionization of the phenoxy group for the coupling reaction was further consolidated by showing that the pH-dependent oxidation of 2-methoxy-phenol (guaiacol) had 50% maximal product formation at pH 7, a value concordant with pKa 7.0 for the ionization of the phenoxy group of this agent. T3 and rT3 synthesis followed mainly the ionization curve of the inner-ring hydroxyl group, indicating that this ring has the greatest influence on hormonogenesis. Since anion formation facilitates the removal of an electron under oxidative conditions, the pH dependence agrees with the involvement of phenoxy radicals in iodothyronine synthesis, a process that most likely also occurs in vivo since it is mainly T4 that is formed in thyroglobulin.
Therapeutic effects of metformin on insulin resistance and hyperandrogenism in polycystic ovary syndrome
Authors: Diamanti-Kandarakis E , Kouli C , Tsianateli T , Bergiele A
Published: January 2005

Evidence suggests that insulin resistance and hyperinsulinaemia are associated with ovarian hyperandrogenism and menstrual irregularities in polycystic ovary syndrome (PCOS). Sixteen obese women with PCOS on a weight-maintaining diet were studied before and after 6 months of therapy with the insulin-sensitizing antidiabetic agent metformin at a dose of 1700 mg per day. Compared with baseline values, glucose utilization was markedly enhanced at 6 months using the two-step euglycaemic-hyperinsulinaemic clamp to measure changes in insulin sensitivity (2.56 +/- 0.32 vs 4.68 +/- 0.49 mg/kg per min, P = 0.0001, when 40 mU insulin/m2 per min was infused, and 6.48 +/- 0.58 vs 9.84 +/- 0.72 mg/kg per min, P = 0.0002, when 400 mU insulin insulin/m2 per min was infused). The improvement in insulin action was accompanied by significant increases in the levels of sex hormone-binding globulin (24.5 +/- 7.2 vs 39.8 +/- 16.2 nmol/l, P = 0.003) and decreases in free testosterone (12.8 +/- 5.8 vs 9.0 +/- 3.0 pmol/l, P = 0.03) and androstenedione (12.9 +/- 5.6 vs 7.3 +/- 1.7 nmol/l, P = 0.003). No significant changes were recorded in body weight. Seven subjects resumed normal menstruation and two cases of spontaneous pregnancy occurred during treatment. Metformin was well tolerated except for one case of flatulence. These results confirm that metformin treatment can lead to improvements in insulin resistance and ovarian hyperandrogenism.