bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and sequence analysis of arginine vasopressin mRNA in normal and Brattleboro rat aortic tissue
Authors: Mechaly I , Macari F , Lautier C , Serrano JJ , Cros G , Grigorescu F
Published: January 2005

Arginine vasopressin (AVP), a hormone of the hypothalamic-pituitary axis, was also localized in peripheral tissues. To explore AVP precursor gene expression at the vascular level, we have investigated gene transcripts by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing in aortic tissue of normal rat and in the particular genetic condition of the homozygous (di/di) Brattleboro rat strain suffering from diabetes insipidus. In these rats, a gene deletion induces an unprocessed AVP precursor in the hypothalamus with undetectable immunoreactive AVP, in contrast to the detection of immunoreactive material at the vascular level. In normal rats, using primers complementary to exon 1 and 3 of the AVP neurophysin precursor gene, RT-PCR and sequencing revealed transcripts of the expected size from aorta, mesenteric artery and hypothalamus with normal, authentic sequences. Removal of aortic endothelium severely reduced the amounts of transcripts, suggesting their main endothelial origin. In Brattleboro rats, transcripts of similar size were obtained from aorta and hypothalamus and sequencing revealed the homozygous deletion (deltaG316) in both tissues, identical to that found in genomic DNA (deltaG1864). While sequence data from normal rats provide the first direct evidence for the presence of AVP precursor transcripts in rat aortic tissue, identification of the deleted sequence of transcripts in Brattleboro rat aorta suggests that tissue-specific mechanisms are operating for the expression of vasopressin neurophysin precursor in peripheral vascular tissue compared with the hypothalamus.
Gestodene and desogestrel do not have a different influence on concentration profiles of ethinylestradiol in women taking oral contraceptives--results of isotope dilution mass spectrometry measurements
Authors: Siekmann L , Siekmann A , Bidlingmaier F , Brill K , Albring M
Published: January 2005

OBJECTIVES: A new method for the quantitative determination of 17alpha-ethinylestradiol-17beta (EE2) in serum is presented here based on the principle of isotope dilution mass spectrometry (IDMS) with [13C]EE2 as internal standard. The technique was used to determine the concentration profiles of EE2 in the serum of female subjects who had taken oral contraceptives with different progestin components. The method has proved to be very reliable with respect to trueness, specificity, precision and detection sensitivity and offers considerable advantages compared with the immunological methods of measurement used to date. STUDY DESIGN: Forty-seven female volunteers took two different oral contraceptives containing EE2 combined with different progestins in accordance with a cross-over design. After the administration of 30 microg EE2 combined with 75 microg gestodene (EE2/GSD) or 150 microg desogestrel (EE2/DES), blood samples were taken from the subjects on certain days and in certain previously specified cycles in the course of 12 h after medication. RESULTS AND CONCLUSIONS: The biometric analysis of the results showed that the concentration profiles of EE2 were in their statistics, significantly equivalent after the administration of either of the two oral contraceptives. The sometimes contradictory results found in former studies after the administration of the different contraceptives were presumably due to the methodological shortcomings of the radioimmunological measurement technique. With the use of the highly accurate and specific technique of IDMS it can now be unequivocally established that the different progestins in the tested oral contraceptives have no influence on the bioavailability of EE2 (area under EE2 serum concentration curves, as usually defined in pharmacokinetics).
Correlation between circulating leptin and luteinizing hormone during the menstrual cycle in normal-weight women
Authors: Teirmaa T , Luukkaa V , Rouru J , Koulu M , Huupponen R
Published: January 2005

OBJECTIVE: Leptin is the hormonal product of the ob gene. It is expressed in adipocytes and participates in the regulation of food intake and metabolism. Since leptin also seems to signal metabolic information to the reproductive system, we studied the association between reproductive hormones and plasma leptin in normal-weight young women. DESIGN: Eight young women with normal menstrual cycles (body mass index (BMI) 21.2 +/- 1.6 kg/m2) and eight young women using hormonal contraception (BMI 21.4 +/- 1.1 kg/m2) were studied. Furthermore, six women with normal menstrual cycles and no hormonal therapy (BMI 20.7 +/- 1.2 kg/m2) were studied around the time of the anticipated ovulation. METHODS: Serum leptin, estradiol, progesterone and luteinizing hormone (LH) concentrations were measured with radioimmunoassays. RESULTS: Serum leptin concentrations were similar at the beginning of the cycle, at the time of the anticipated ovulation and at the end of the menstrual cycle (10.2 +/- 7.1, 10.7 +/- 7.0 and 11.8 +/- 6.9 microg/l respectively). There was an association between leptin and LH concentrations (r= 0.37, P< 0.01) when values recorded during different time points during the cycle were plotted with each other. There was no change in serum leptin in samples taken at different times of the cyclic treatment with an oral contraceptive. There was no significant difference in mean serum leptin concentrations between women using oral contraceptives and women with no hormonal therapy. CONCLUSIONS: There is a link between serum leptin and LH concentrations during the menstrual cycle. Variations in circulating estrogen and/or progesterone concentrations have no major influence on circulating leptin in young female subjects.
Variability of Ha-ras (codon 12) proto-oncogene mutations in diverse thyroid cancers
Authors: Bouras M , Bertholon J , Dutrieux-Berger N , Parvaz P , Paulin C , Revol A
Published: January 2005

Structural alterations to proto-oncogene sequences may be involved in the pathogenesis of human thyroid neoplasms. We studied 128 thyroid tumours (35 benign and 93 malignant) for ras gene point mutations in three different codons (12, 13 and 61) using a restriction fragment length polymorphism technique and direct sequencing of double-stranded DNA on polymerase chain-reaction-amplified tumour DNA. We found a high frequency of ras mutation for the Ha-ras codon 12 in follicular adenomas (7 of 35), particularly in atypical adenomas (5 of 17), in follicular carcinomas (6 of 19), with a high percentage for Hurthle cell carcinomas (6 of 11), and in papillary carcinomas (4 of 66). Point mutations for other ras genes in different codons studied were weak to absent. No mutation was found in undifferentiated carcinomas (n = 8). The predominant amino acid substitution both in the adenomas and in the differentiated tumours was glycine to valine (GGC to GTC) at position 12 of the Ha-ras gene. Our results obtained on a large series confirm the frequent occurrence of Ha-ras codon 12 gene mutations both in adenomas and in carcinomas. The frequency of ras mutations is linked to the geographical origin of the population studied and varies (0-85%) from one cancer type to another according to published data. Therefore, these mutations are merely an expression of cellular transformation.
Human leptin forms complexes with alpha 2-macroglobulin which are recognized by the alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein
Authors: Birkenmeier G , Kampfer I , Kratzsch J , Schellenberger W
Published: January 2005

OBJECTIVE: To identify binding proteins of leptin in human plasma. METHODS: Binding was evaluated by electrophoresis, size exclusion chromatography (SEC), Western blotting, and radioisotope labeling. Quantification of leptin and the different forms of alpha2-macroglobulin (alpha2-M) was performed by ELISA. RESULTS: Leptin interacts with the proteinase inhibitor, alpha2-M. 125I-labeled leptin specifically binds to the transformed inhibitor, which arises by reaction with proteinases or with reactive primary amines. No leptin binding was observed to the native alpha2-M, which abundantly occurs in plasma. The complex formation between leptin and alpha2-M was found to proceed within minutes and was stable, as it resisted separation by SEC and electrophoresis. The Kd of the complex was 2.14 +/- 0.78 micromol/l. Complex formation with transformed alpha2-M did not interfere with the immunological determination of leptin in plasma. The leptin-alpha2-M complex was found to be recognized by the alpha2-M receptor/low density lipoprotein receptor-related protein. By computer analysis, a simple model is presented showing that the degree of transformation of alpha2-M may significantly influence the leptin concentration in blood. CONCLUSIONS: The proteinase inhibitor, alpha2-M, may act as a leptin-binding protein in human plasma. Binding of leptin to transformed alpha2-M and its rapid clearance by the alpha2-M receptor may significantly influence the bioavailability of leptin in human plasma.
Neuronal histamine and expression of corticotropin-releasing hormone, vasopressin and oxytocin in the hypothalamus: relative importance of H1 and H2 receptors
Authors: Kjaer A , Larsen PJ , Knigge U , Jorgensen H , Warberg J
Published: January 2005

Centrally administered histamine (HA) stimulates the secretion of the pro-opiomelanocortin-derived peptides ACTH and beta-endorphin as well as prolactin. The effect of HA on secretion of these adenohypophysial hormones is indirect and may involve activation of hypothalamic neurons containing corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) or oxytocin (OT). We studied the effect of activating central HA receptors by central infusion of HA, HA agonists or antagonists on expression of CRH, AVP and OT mRNA in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Intracerebroventricular infusion of HA (270 nmol), the H1-receptor agonist 2-thiazolylethylamine or the H2-receptor agonist 4-methylhistamine increased the level of CRH mRNA in the PVN, and OT mRNA in the SON. In contrast, none of these compounds had any effect on expression of AVP mRNA in the PVN or SON. Administration of the H1-receptor antagonist mepyramine or the H2-receptor antagonist cimetidine had no effect on basal expression of CRH, AVP or OT mRNA in the PVN and/or SON except for a slight inhibitory effect of cimetidine on CRH mRNA expression in the PVN. Pretreatment with mepyramine or cimetidine before HA administration inhibited the HA-induced increase in OT mRNA levels but had no effect on the HA-induced increase in CRH mRNA levels in the PVN. We conclude that HA stimulates hypothalamic CRH and OT neurons by increasing mRNA levels, and this effect seems to be mediated via activation of both HA H1 and H2 receptors.
The one microgram adrenocorticotropin test in the assessment of hypothalamic-pituitary-adrenal function
Authors: Ambrosi B , Barbetta L , Re T , Passini E , Faglia G
Published: January 2005

The possibility of assessing hypothalamic-pituitary-adrenal (HPA) function by the standard ACTH test (250 microg) has been widely discussed in the past years and compared with the role of the insulin tolerance test (ITT). Recently, it was shown that low doses of ACTH, such as 1 microg i.v., induce a maximal adrenal response and, by reducing the discrepancies compared with the ITT also allow one to detect mild forms of secondary hypoadrenalism. In the present study the 1 microg ACTH test was performed in patients with hypothalamic-pituitary disease in order to assess adrenal function, and the results have been compared with those obtained after the insulin test. Fifty-seven patients (31 men and 26 women, aged 19-73 years) with hypothalamic-pituitary diseases were studied: 51 patients were affected with pituitary tumor and 6 patients had hypothalamic disorders. All these patients and 18 healthy volunteers (7 men and 11 women, aged 19-46 years) received 1 microg i.v. ACTH injection. In addition, the ITT (0.1-0.15 U/kg body weight) was performed in all patients. In normal subjects mean cortisol levels significantly (P<0.001) increased from a baseline of 393+/-43 nmol/l to a peak of 770+/-41 nmol/l after 1 microg ACTH. In 44 patients with hypothalamic-pituitary disease 1 microg ACTH caused a cortisol rise similar to that of normal subjects (from 332+/-17 to 769+/-24 nmol/l; P<0.001), while an impaired response (from 124+/-23 to 312+/-46 nmol/l) was observed in 13 cases (23%), 7 of them with low morning cortisol levels (10-127 nmol/l) and 6 with basal values at the lower limit of normality. The cortisol response to ITT was compared with that obtained after the 1 microg ACTH test: 10 patients failed both challenges, 4 patients who passed the ACTH test failed the ITT, while 3 patients who failed the ACTH test passed the ITT. The 23 out of 57 patients (40%) who showed a cortisol peak greater than 750 nmol/l after 1 microg ACTH had a normal response to ITT. A positive correlation between cortisol peaks after ACTH and after insulin was also found (r = 0.68, P<0.001). Assuming a 100% accuracy of ITT, the low dose ACTH test yielded a 71% sensitivity and a 93% specificity. In conclusion, the low-dose ACTH test is a useful, safe and inexpensive tool for the initial assessment of HPA function in patients with hypothalamic-pituitary disease. In fact, the ITT is unnecessary when cortisol peaks are greater than 750 nmol/l after 1 microg ACTH and also when very low cortisol basal levels indicate an overt hypoadrenalism. Within these limits the ITT is mandatory and its important role in the recognition of secondary adrenal failure is further confirmed.
Evolution of childhood central diabetes insipidus into panhypopituitarism with a large hypothalamic mass: is 'lymphocytic infundibuloneurohypophysitis' in children a different entity?
Authors: Maghnie M , Genovese E , Sommaruga MG , Arico M , Locatelli D , Arbustini E , Pezzotta S , Severi F
Published: January 2005

We report on a 15-year-old girl who had presented with acute onset central diabetes insipidus at the age of 8 years; this was followed by growth failure due to acquired growth hormone deficiency. Initial magnetic resonance imaging showed a uniformly enlarged pituitary stalk and absence of posterior pituitary hyperintensity. Frequent patient examination and magnetic resonance imaging gave unchanged results until after 5 years a large hypothalamic mass and panhypopituitarism were found. Dynamic magnetic resonance imaging documented hypothalamic-pituitary vasculopathy. Histopathological examination revealed perivascular inflammatory lymphoplasmic infiltrates with no granulomatosis or necrosis and negative staining for S-100 protein, suggesting autoimmune inflammatory disease (lymphocytic infundibuloneurohypophysitis?). The response to glucocorticoid pulses (30 mg/kg per day for 3 days i.v.) was favorable. the hypothalamic mass being halved and partial anterior pituitary function recovery maintained for 2 years after the start of treatment. We suggest that long-term surveillance is needed for isolated and chronic thickening of the pituitary stalk and that dynamic magnetic resonance imaging can contribute to the demonstration of hypothalamic-pituitary vascular impairment associated with local vasculitis.
Growth hormone-releasing peptide-2 infusion synchronizes growth hormone, thyrotrophin and prolactin release in prolonged critical illness
Authors: Van den Berghe G , Wouters P , Bowers CY , de Zegher F , Bouillon R , Veldhuis JD
Published: January 2005

OBJECTIVE: During prolonged critical illness, nocturnal pulsatile secretion of GH, TSH and prolactin (PRL) is uniformly reduced but remains responsive to the continuous infusion of GH secretagogues and TRH. Whether such (pertinent) secretagogues would synchronize pituitary secretion of GH, TSH and/or PRL is not known. DESIGN AND METHODS: We explored temporal coupling among GH, TSH and PRL release by calculating cross-correlation among GH, TSH and PRL serum concentration profiles in 86 time series obtained from prolonged critically ill patients by nocturnal blood sampling every 20 min for 9 h during 21-h infusions of either placebo (n=22), GHRH (1 microg/kg/h; n=10), GH-releasing peptide-2 (GHRP-2; 1 microg/kg/h; n=28), TRH (1 microg/kg/h; n=8) or combinations of these agonists (n=8). RESULTS: The normal synchrony among GH, TSH and PRL was absent during placebo delivery. Infusion of GHRP-2, but not GHRH or TRH, markedly synchronized serum profiles of GH, TSH and PRL (all P< or =0.007). After addition of GHRH and TRH to the infusion of GHRP-2, only the synchrony between GH and PRL was maintained (P=0.003 for GHRH + GHRP-2 and P=0.006 for TRH + GHRH + GHRP-2), and was more marked than with GHRP-2 infusion alone (P=0.0006 by ANOVA). CONCLUSIONS: The nocturnal GH, TSH and PRL secretory patterns during prolonged critical illness are herewith further characterized to include loss of synchrony among GH, TSH and PRL release. The synchronizing effect of an exogenous GHRP-2 drive, but not of GHRH or TRH, suggests that the presumed endogenous GHRP-like ligand may participate in the orchestration of coordinated anterior pituitary hormone release.
Long-term results of GH therapy in GH-deficient children treated before 1 year of age
Authors: Huet F , Carel JC , Nivelon JL , Chaussain JL
Published: January 2005

OBJECTIVES: To evaluate the long-term effects of GH therapy in early diagnosed GH-deficient patients treated before 1 year of age. Study design: We studied all 59 patients (33 males) recorded by Association France-Hypophyse and treated with GH (0.50+/-0.15 IU/kg (S.D.) per week) before 1 year of age. Clinical presentation and growth parameters under GH treatment were analyzed. RESULTS: Neonatal manifestations of hypopituitarism were frequent: hypoglycemia (n=50), jaundice (n=25) and micropenis (n=17/33). Although birth length was moderately reduced (-0.9+/-1.4), growth retardation at diagnosis (5.8+/-3.8 months) was severe (-3.5+/-1.9 standard deviation scores (SDS)). Fifty patients (85%) had thyrotropin and/or corticotropin deficiency. After a mean duration of GH therapy of 8.0+/-3.6 years, change in height SDS was +3.11+/-2.06 S.D., exceeding 4 SDS in 19 patients. Only 9 patients (15%) did not reach a height of -2 S.D. for chronological age and 20 patients (34%) exceeded their target height. Pretreatment height SDS was independently associated with total catch-up growth. CONCLUSION: Conventional doses of GH allow normalization of height in patients with early GH deficiency and treatment.
Changes in body composition and leptin levels during growth hormone (GH) treatment in short children with various GH secretory capacities
Authors: Matsuoka H , Fors H , Bosaeus I , Rosberg S , Albertsson-Wikland K , Bjarnason R
Published: January 2005

OBJECTIVE: The aim of this study was to follow changes in body composition, estimated by dual-energy X-ray absorptiometry (DXA), in relation to changes in leptin during the first year of GH therapy in order to test the hypothesis that leptin is a metabolic signal involved in the regulation of GH secretion in children. DESIGN AND METHODS: In total, 33 prepubertal children were investigated. Their mean (S.D.) chronological age at the start of GH treatment was 11.5 (1.6) years, and their mean height was -2.33 (0.38) S.D. scores (SDS). GH was administered subcutaneously at a daily dose of 0.1 (n=26) or 0.2 (n=7) IU/kg body weight. Ten children were in the Swedish National Registry for children with GH deficiency, and twenty-three children were involved in trials of GH treatment for idiopathic short stature. Spontaneous 24-h GH secretion was studied in 32 of the children. In the 24-h GH profiles, the maximum level of GH was determined and the secretion rate estimated by deconvolution analysis (GHt). Serum leptin levels were measured at the start of GH treatment and after 10 and 30 days and 3, 6 and 12 months of treatment. Body composition measurements, by DXA, were performed at baseline and 12 months after the onset of GH treatment. RESULTS: After 12 months of GH treatment, mean height increased from -2.33 to -1.73 SDS and total body fat decreased significantly by 3.0 (3.3)%. Serum leptin levels were decreased significantly at all time points studied compared with baseline. There was a significant correlation between the change in total body fat and the change in serum leptin levels during the 12 months of GH treatment, whereas the leptin concentration per unit fat mass did not change. In a multiple stepwise linear regression analysis with 12 month change in leptin levels as the dependent variable, the percentage change in fat over 12 months, the baseline fat mass (%) of body mass and GHt accounted for 24.0%, 11.5% and 12.2% of the variability respectively. CONCLUSIONS: There are significant correlations between changes in leptin and fat and endogenous GH secretion in short children with various GH secretory capacities. Leptin may be the messenger by which the adipose tissue affects hypothalamic regulation of GH secretion.
Trans-sphenoidal surgery for microprolactinoma: an acceptable alternative to dopamine agonists?
Authors: Turner HE , Adams CB , Wass JA
Published: January 2005

AIMS: Reported cure rates following trans-sphenoidal surgery for microprolactinoma are variable and recurrence rates in some series are high. We wished to examine the cure rate of trans-sphenoidal surgery for microprolactinoma, and to assess the long-term complications and recurrence rate. DESIGN: A retrospective review of the outcome of trans-sphenoidal surgery for microprolactinoma, performed by a single neurosurgeon at a tertiary referral centre between 1976 and 1997. PATIENTS: All thirty-two patients operated on for microprolactinoma were female, with a mean age of 31 years (range 16-49). Indications for surgery were intolerance of dopamine agonists in ten (31%), resistance in six (19%) and resistance and intolerance in four (12.5%). Two patients were from countries where dopamine agonists were unavailable. RESULTS: The mean pre-operative prolactin level was 2933 mU/l (range 1125-6000). All but 1 had amenorrhoea or oligomenorrhoea, with galactorrhoea in 15 (46.9%). Twenty-five (78%) were cured by trans-sphenoidal surgery, as judged by a post-operative serum prolactin in the normal range. During a mean follow-up of 70 months (range 2 months to 16 years) there was one recurrence at 12 years. Post-operatively, one patient became LH deficient, two patients became cortisol deficient and two became TSH deficient. Out of 21 patients tested for post-operative growth hormone deficiency, 6 (28.6%) were deficient. Five patients developed post-operative diabetes insipidus which persisted for greater than 6 months. There were no other complications of surgery. The estimated cost of uncomplicated trans-sphenoidal surgery, and follow-up over 10 years, was similar to that of dopamine agonist therapy. CONCLUSION: In patients with hyperprolactinaemia due to a pituitary microprolactinoma, transsphenoidal surgery by an experienced pituitary surgeon should be considered as a potentially curative procedure. The cost of treatment over a 10 year period is similar in uncomplicated cases to long-term dopamine agonist therapy.
Why is the retention of gonadotrophin secretion common in children with panhypopituitarism due to septo-optic dysplasia?
Authors: Nanduri VR , Stanhope R
Published: January 2005

Septo-optic dysplasia (De Morsier syndrome) is a developmental anomaly of mid-line brain structures and includes optic nerve hypoplasia, absence of the septum pellucidum and hypothalamo-pituitary abnormalities. We describe seven patients (four female, three male) who had at least two out of the three features necessary for the diagnosis of septo-optic dysplasia. Four patients had hypopituitarism and yet normal gonadotrophin secretion: one of these also had anti-diuretic hormone insufficiency; three had isolated GH deficiency and yet had premature puberty, with the onset of puberty at least a year earlier than would have been expected for their bone age. In any progressive and evolving anterior pituitary lesion it is extremely unusual to lose corticotrophin-releasing hormone/ACTH and TRH/TSH secretion and yet to retain gonadotrophin secretion. GnRH neurons develop in the nasal mucosa and migrate to the hypothalamus in early fetal life. We hypothesise that the arrival of GnRH neurons in the hypothalamus after the development of a midline hypothalamic defect may explain these phenomena. Progress in spontaneous/premature puberty in children with De Morsier syndrome may have important implications for management. The combination of GH deficiency and premature puberty may allow an apparently normal growth rate but with an inappropriately advanced bone age resulting in impaired final stature. GnRH analogues may be a therapeutic option. In conclusion, some patients with De Morsier syndrome appear to retain the ability to secrete gonadotrophins in the face of loss of other hypothalamic releasing factors. The migration of GnRH neurons after the development of the midline defect may be an explanation.
On the meaning of low-dose ACTH(1-24) tests to assess functionality of the hypothalamic-pituitary-adrenal axis
Authors: Darmon P , Dadoun F , Frachebois C , Velut JG , Boullu S , Dutour A , Oliver C , Grino M
Published: January 2005

To analyse further the ACTH(1-24) low-dose test, which is of clinical interest, we have examined the dose-response relationship between plasma ACTH(1-24) and cortisol concentrations after i.v. administration of increasing doses (1, 5 or 250 microg) of ACTH(1-24) as a bolus. In addition, we have measured plasma ACTH(1-39) and cortisol levels after an insulin tolerance test (ITT). Although there was a dose response relationship between plasma ACTH(1-24) immunoreactivity and the dose injected, cortisol peaks were comparable, but lower than those reached after an ITT. Under these experimental conditions, an increase in plasma ACTH as low as 13 pmol/l (i.e. the increase obtained with the 1 microg dose) induced a near maximal cortisol response. Following injection of 1 microg ACTH(1-24), peak ACTH values were short lasting, similar to physiological daily bursts. After injection of 5 microg ACTH(1-24), plasma ACTH concentrations were higher than those reached during an ITT, but clearly shorter lasting. Injection of 250 microg ACTH(1-24) induced strikingly supraphysiological levels of plasma ACTH. We conclude that neither regular nor low-dose ACTH tests can fully reproduce the ITT. Our observations strongly suggest that the low-dose ACTH(1-24) test (1 microg) can be useful to estimate the adrenal sensitivity under basal, physiological conditions.
The treatment of insulin resistance does not improve adrenal cytochrome P450c17alpha enzyme dysregulation in polycystic ovary syndrome
Authors: Unluhizarci K , Kelestimur F , Sahin Y , Bayram F
Published: January 2005

OBJECTIVE: To determine whether metformin. when given to non-diabetic women with polycystic ovary syndrome (PCOS), results in a reduction of insulin resistance and hyperinsulinemia while body weight is maintained. Also we aimed to see whether the reduction in insulin levels attenuates the activity of adrenal P450c17alpha enzyme in patients with PCOS. DESIGN: We investigated the 17-hydroxyprogesterone (17-OHP) and androstenedione responses to ACTH, insulin responses to an oral glucose tolerance test (OGTT) and glucose disposal rate in an insulin tolerance test before and after metformin therapy (500 mg, orally, twice daily, for 12 weeks). METHODS: The presence of hyperinsulinemia in 15 women with PCOS was demonstrated by an OGTT and results were compared with those of 10 healthy women. Insulin sensitivity was measured by the rate of endogenous glucose disposal after i.v. bolus injection of insulin. 17-OHP and androstenedione responses to ACTH were measured in all the women with PCOS and the normal women. RESULTS: Women with PCOS were hyperinsulinemic (102.0+/-13.0 (S.E.M.) VS 46.2+/-4.4 pmol/l) and hyperandrogenemic (free testosterone 15.3+/-1.7 vs 7.9+/-0.6 nmol/l; androstenedione 11.8+/-0.8 vs 8.2+/-0.6 nmol/l) and more hirsute (modified Ferriman-Gallwey score, 17.7+/-1.6 vs 3.0+/-0.3) than healthy women. In addition, women with PCOS had higher 17-OHP and androstenedione responses to ACTH when compared with healthy women. Metformin therapy resulted in some improvement in insulin sensitivity and reduced the basal and post-glucose load insulin levels. But 17-OHP and androstenedione responses to ACTH were unaltered in response to metformin. CONCLUSIONS: PCOS is characterized by hyperactivity of the adrenal P450c17alpha enzyme and insulin resistance. It seems that there is no direct relationship between insulin resistance and adrenal P450c17alpha enzyme dysregulation.
True hermaphroditism associated with microphthalmia
Authors: Hayashi T , Kageyama Y , Ishizaka K , Tsujii T , Oshima H
Published: January 2005

A 4-year-old boy with an undescending left testis, penoscrotal hypospadia and bilateral microphthalmia was admitted to our hospital. Chromosome analysis revealed a karyotype of 46, XX del(x)(p2 2,31) and the sex-determining region of the Y chromosome (SRY) was negative. The right testis was located in the scrotum and a left cystic ovary-like gonad, a salpinx and a unicorn uterus were found in the left inguinal canal. Histologically the gonad was an ovotestis in which primordial follicles covered infantile seminiferous tubules. Microphthalmia is observed in some congenital syndromes caused by interstitial deletion of the X chromosome. This case suggested that the short arm of the X chromosome was involved in the differentiation of the gonad. Very closely located follicles and infantile seminiferous tubules indicated that induction of meiosis in the fetus was controlled by the local microenvironment in follicles and seminiferous tubules, and not by the systemic hormonal condition.
Islet amyloid polypeptide/amylin messenger RNA and protein expression in human insulinomas in relation to amyloid formation
Authors: van Hulst KL , Oosterwijk C , Born W , Vroom TM , Nieuwenhuis MG , Blankenstein MA , Lips CJ , Fischer JA , Hoppener JW
Published: January 2005

OBJECTIVE: Islet amyloid polypeptide (IAPP), also named amylin, is the predominant protein component of amyloid deposits in human islet beta cell tumours of the pancreas (insulinomas). IAPP is co-produced with insulin by islet beta cells. We investigated IAPP expression in relation to insulin expression and to amyloid formation in eleven insulinomas. DESIGN AND METHODS: RNA and protein extracts were prepared from the same pieces of tumour tissue, and from specimens of two normal human pancreata. IAPP and insulin mRNA and peptide content were quantified using Northern blot analysis and radioimmunoassay (RIA) respectively. Molecular forms of IAPP immunoreactivity were analysed by reversed-phase high-performance liquid chromatography (HPLC). The presence of islet hormones and of amyloid was assessed by (immuno)histochemical staining of paraffin sections. Plasma levels of IAPP and insulin prior to tumour resection were determined by RIA. RESULTS: IAPP and insulin mRNA and peptide content varied widely between the tumour specimens, and there was considerable intratumour heterogeneity of peptide content. HPLC analysis indicated correct proteolytic processing of the IAPP precursor protein. Amyloid deposits were detected only in the three tumours with the highest IAPP content. In contrast to insulin, plasma levels of IAPP were not elevated in the insulinoma patients. CONCLUSIONS: The spectrum of hormone production by insulinomas cannot be inferred from only a few tissue sections due to intratumour heterogeneity. Expression of the IAPP and insulin genes is not coupled in insulinomas, which produce properly processed mature IAPP. In addition to IAPP overproduction, additional factors such as intracellular accumulation of IAPP are involved in amyloidogenesis in insulinomas.
Treatment of streptozotocin-induced diabetic rats with vanadate and phlorizin prevents the over-expression of the liver insulin receptor gene
Authors: Amessou M , Bortoli S , Liemans V , Collinet M , Desbuquois B , Brichard S , Girard J
Published: January 2005

Administration of vanadate, an insulinomimetic agent, has been shown to normalize the increased number of insulin receptors in the liver of streptozotocin-induced diabetic rats. In the present study, the effects of vanadate on various steps of expression of the liver insulin receptor gene in diabetic rats have been analyzed and compared with those of phlorizin, a glucopenic drug devoid of insulinomimetic properties. Livers of rats killed 23 days after streptozotocin injection showed a 30-40% increase in the number of cell surface and intracellular insulin receptors, a 50-90% increase in the levels of 9.5 and 7.5 kb insulin receptor mRNA species, and a 20% decrease in the relative abundance of the A (exon 11-) insulin receptor mRNA isotype. Daily administration of vanadate or phlorizin from day 5 to day 23 prevented the increase in insulin receptor number and mRNA level, and vanadate treatment also normalized receptor mRNA isotype expression. Unlike observations in vivo, vanadate and phlorizin differentially affected the expression of the insulin receptor gene in Fao hepatoma cells. Vanadate treatment (0.5 mmol/l for 4 h) decreased the levels of the 9.5 and 7.5 kb insulin receptor transcripts by at least twofold, without affecting the relative abundance of the A insulin receptor mRNA isotype. In contrast, phlorizin treatment (5 mmol/l for 4 h) slightly increased or did not affect the levels of the 9.5 and 7.5 kb insulin receptor transcripts respectively, and increased by twofold the relative expression of the A insulin receptor mRNA isotype. It is suggested that, although mediated in part by a reversal of hyperglycemia, normalization of liver insulin receptor gene expression by vanadate treatment in diabetic rats may also involve a direct inhibitory effect of this drug on gene expression.
L-arginine stimulation of glucose-induced insulin secretion through membrane depolarization and independent of nitric oxide
Authors: Thams P , Capito K
Published: January 2005

The mechanism of L-arginine stimulation of glucose-induced insulin secretion from mouse pancreatic islets was studied. At 16.7 mmol/l glucose, L-arginine (10 mmol/l) potentiated both phases 1 and 2 of glucose-induced insulin secretion. This potentiation of glucose-induced insulin secretion was mimicked by the membrane depolarizing agents tetraethylammonium (TEA, 20 mmol/l) and K+ (60 mmol/l), which at 16.7 mmol/l glucose obliterated L-arginine (10 mmol/l) modulation of insulin secretion. Thus L-arginine may potentiate glucose-induced insulin secretion by stimulation of membrane depolarization. At 3.3 mmol/l glucose, L-arginine (10 mmol/l) failed to stimulate insulin secretion. In accordance with membrane depolarization by the electrogenic transport of L-arginine, however, L-arginine (10 mmol/l) stimulation of insulin secretion was enabled by the K+ channel inhibitor TEA (20 mmol/l), which potentiates membrane depolarization by L-arginine. Furthermore, L-arginine (10 mmol/l) stimulation of insulin secretion was permitted by forskolin (10 micromol/l) or tetradecanoylphorbol 13-acetate (0.16 micromol/l), which, by activation of protein kinases A and C respectively sensitize the exocytotic machinery to L-arginine-induced Ca2+ influx. Thus glucose may sensitize L-arginine stimulation of insulin secretion by potentiation of membrane depolarization and by activation of protein kinase A or protein kinase C. Finally, L-arginine stimulation of glucose-induced insulin secretion was mimicked by NG-nitro-L-arginine methyl ester (10 mmol/l), which stimulates membrane depolarization but inhibits nitric oxide synthase, suggesting that L-arginine-derived nitric oxide neither inhibits nor stimulates insulin secretion. In conclusion, it is suggested that L-arginine potentiation of glucose-induced insulin secretion occurs independently of nitric oxide, but is mediated by membrane depolarization, which stimulates insulin secretion through protein kinase A- and C-sensitive mechanisms.
Insulin and TSH promote growth in size of PC Cl3 rat thyroid cells, possibly via a pathway different from DNA synthesis: comparison with FRTL-5 cells
Authors: Kimura T , Dumont JE , Fusco A , Golstein J
Published: January 2005

In the rat thyroid cell lines PC Cl3, FRTL- 5 and WRT, proliferation is mainly regulated by insulin or IGF, and TSH. However, the mechanism regulating cell mass doubling prior to division is still unknown. Our laboratory has shown that in dog thyroid cells insulin promotes growth in size while TSH in the presence of insulin triggers DNA replication. In the absence of insulin, TSH has no effect on cell growth. In this report we investigated insulin action on both cell mass and DNA synthesis and its modulation by TSH and insulin in PC Cl3 and FRTL-5 cells. In PC Cl3 cells, insulin activated not only DNA synthesis but also protein synthesis and accumulation. Although TSH potentiated the stimulation of DNA synthesis induced by insulin, enhancement of protein synthesis by both agents was additive. All TSH effects were reproduced by forskolin. Similar effects were also obtained in FRTL-5 cells. This suggests that insulin and TSH, via cAMP, modulate both growth in size and DNA replication in these cell lines. Lovastatin, which blocks 3-hydroxy-3-methylglutaryl coenzyme A reductase, decreased the induction of DNA synthesis, but not of protein synthesis induced by insulin or TSH in PC Cl3 cells. In FRTL-5 cells, lovastatin reduced protein and DNA synthesis stimulated by insulin but not TSH-induced protein synthesis. Taking these data together, we propose that insulin and/or TSH both modulate cell mass doubling and DNA synthesis in these cell lines, presumably via different pathways, and that there are at least two pathways which regulate growth in size in FRTL-5 thyroid cells: one triggered by insulin, which is lovastatin sensitive, and the other activated by TSH, which is not sensitive to lovastatin.
Thyroid volumes and urinary iodine in Swiss school children, 17 years after improved prophylaxis of iodine deficiency
Authors: Burgi H , Portmann L , Podoba J , Vertongen F , Srbecky M
Published: January 2005

Salt iodine content in Switzerland was raised from 7.5 to 15 mg per kg in 1980, and since then dietary iodine intake has been considered to be sufficient, even though a slight decrease due to imported food has recently been reported. The aim of this study was to establish normal values for thyroid volumes of school children who can be assumed to have had a sufficient iodine intake all their lifetime. Moreover. the present investigation was undertaken to verify that iodine sufficiency had been achieved equally in two regions each served by one of the two Swiss salt producers. Mean iodine concentration in urine spot samples from school children was 16.1 microg/dl, and it was identical in both the city of Lausanne (n=215) and the city of Solothurn (n=208). Thus it can be stated that in both cities (served by two different salt producers) iodine intake is equal and sufficient. Accordingly, thyroid volumes measured by ultrasound in school children aged 6 to 16 years were the same in both Lausanne (n=202) and Solothurn (n=207). Moreover, the age-adjusted median volumes at the 97th percentiles closely agree with and validate provisional international reference values recently proposed by the World Health Organisation and by the International Council for Control of Iodine Deficiency Disease.
Interactions between the neuropeptide Y system and the hypothalamic-pituitary-adrenal axis
Authors: Krysiak R , Obuchowicz E , Herman ZS
Published: January 2005

The aim of this paper is to review the present knowledge of interactions between the neuropeptide Y (NPY) system and the hypothalamic-pituitary-adrenal (HPA) axis. On the basis of in vitro and in vivo studies of various animal species, we review the effects of NPY on all levels of HPA axis activity. We also describe the effects of glucocorticosteroids on the NPY system in the hypothalamus, including interactions between glucocorticosteroids and insulin. On the basis of available literature, we discuss the role of these interactions in the control of food intake and in the pathogenesis of obesity.
GH-binding protein in obese men with varying glucose tolerance: relationship to body fat distribution, insulin secretion and the GH-IGF-I axis
Authors: Nam SY , Kim KR , Song YD , Lim SK , Lee HC , Huh KB
Published: January 2005

Bioelectrical impedance for measurement of total body fat and computed tomography for visceral and subcutaneous fat at umbilicus levels were performed in 34 obese and 10 lean men. Insulin secretion in response to an oral glucose tolerance test (OGTT) and a GH stimulation test by L-dopa, growth hormone-binding protein (GHBP) and IGF-I were measured. Obese subjects were divided into three groups according to the OGTT. The obese type II diabetes mellitus group had the highest GHBP levels and the most visceral fat. GHBP levels were most strongly correlated with the ratio of visceral fat area to body weight (VWR) above any other parameters (r = 0.725, P<0.001). The insulin and free fatty acid (FFA) areas under curves (AUC) during the OGTT, and the IGF-I level, were also positively correlated with GHBP levels (r = 0.474, P<0.005; r = 0.572, P<0.005; r = 0.453. P<0.005). GH-AUC to the L-dopa stimulation test was negatively correlated with GHBP levels (r = -0.432. P<0.005). Stepwise multiple linear regression analysis showed that VWR, FFA-AUC and insulin-AUC significantly contributed to the variability of GHBP (r2 = 0.58). In conclusion, we demonstrated that: (i) visceral fat amount mainly determined GHBP levels in obese men with varying glucose tolerance: (ii) hyperglycemia per se did not influence the GHBP level, whereas insulin and FFA could play a role in regulation of GHBP: and (iii) although GH was not the main regulator of GHBP, the unchanged IGF-I level despite GH hyposecretion suggests that increased GHBP levels reflect GH hypersensitivity in order to compensate for decreased GH secretion in obesity.
Overexpression of fibroblast growth factor receptor 3 in a human thyroid carcinoma cell line results in overgrowth of the confluent cultures
Authors: Onose H , Emoto N , Sugihara H , Shimizu K , Wakabayashi I
Published: January 2005

Recent reports indicate that a gain-of-function mutation in fibroblast growth factor receptor 3 (FGFR-3) inhibits cell growth in the cartilaginous growth plates. These results suggest that FGFR-3 may be the receptor transducing growth inhibitory signals. Using reverse transcription-PCR we examined seven papillary thyroid carcinomas to determine FGFR-3 expression. Six out of the seven papillary carcinomas expressed FGFR-3. To clarify the role of FGFR-3 in thyroid carcinoma, FGFR-3 was overexpressed in an established human papillary thyroid carcinoma cell line. High levels of FGFR-3 protein were identified in cells stably transfected with the vector containing FGFR-3 cDNA. The specific binding of 125I-FGF-2 of these cells was threefold higher than that of control cells. Growth rates of cells overexpressing FGFR-3 were similar to those of control cells. However, cells overexpressing FGFR-3 continued to grow beyond the density at which control cells stopped proliferating. These results suggest that FGFR-3 in thyroid carcinoma is not involved strongly in the cell proliferation mechanism but may contribute to the malignant extension of some of the carcinomas by modifying cell contact signaling.
Analysis of the relationship between fasting serum leptin levels and estimates of beta-cell function and insulin sensitivity in a population sample of 380 healthy young Caucasians
Authors: Echwald SM , Clausen JO , Hansen T , Urhammer SA , Hansen L , Dinesen B , Borch-Johnsen K
Published: January 2005

OBJECTIVE: Circulating leptin levels correlate positively with the degree of obesity and prolonged hyperinsulinaemia increases serum leptin levels. Moreover, insulin secreting beta-cells express functional leptin receptors indicating a functional relationship between leptin and insulin. The aim of this study was to examine the relationship between fasting serum leptin levels and measures of insulin sensitivity and beta-cell function in a population-based sample of 380 young healthy Caucasians. DESIGN AND METHODS: Multiple regression analysis was employed to analyse the relationship between fasting serum leptin levels and levels of fasting serum insulin, insulin sensitivity index and acute insulin response (AIR) in a population-based study of 380 young healthy Caucasians who underwent a combined intravenous glucose and tolbutamide tolerance test. RESULTS AND CONCLUSION: Serum leptin levels were positively correlated to measures of adiposity and were 3.2 times higher in women than in men (P<0.00001). In multiple regression analyses adjusting for age, percentage body fat, waist circumference and maximal aerobic capacity, a significant positive correlation was observed between the fasting serum leptin concentrations and both fasting serum insulin levels (P<0.0001) and AIR (P = 0.014) for women. No significant interrelation of these variables was found in men. However, for both genders a significant negative correlation was observed between fasting serum leptin levels and measures of insulin sensitivity index (P = 0.007).
Interactions of ovarian steroids with pituitary adenylate cyclase-activating polypeptide and GnRH in anterior pituitary cells
Authors: Ortmann O , Asmus W , Diedrich K , Schulz KD , Emons G
Published: January 2005

Pituitary adenylate cyclase-activating polypeptide (PACAP) releases LH and FSH from anterior pituitary cells. Although this effect is relatively weak, it has a strong sensitizing action on GnRH-induced gonadotropin secretion. Here we investigated the possibility that ovarian steroids, which are well-known modulators of LH secretion, interact with PACAP and GnRH in pituitary gonadotrophs. Rat pituitary cells were treated for 48 h with vehicle, 1 nmol/l estradiol, 1 nmol/l estradiol + 100 nmol/l progesterone or 48 h with 1 nmol/l estradiol and 4 h with 100 nmol/l progesterone. The cells were stimulated for 3 h with 1 nmol/l GnRH or 100 nmol/l PACAP. Estradiol treatment alone enhanced basal as well as GnRH- or PACAP-stimulated LH secretion. LH release was facilitated by additional short-term progesterone treatment. Long-term treatment with estradiol and progesterone led to reduced LH responses to GnRH and PACAP. Neither treatment paradigms affected cAMP production. However, estradiol treatment led to enhanced cAMP accumulation in quiescent or GnRH-stimulated cells. PACAP-induced increases of cAMP production were inhibited by estradiol treatment. After 7-h preincubation with 10 nmol/l PACAP, cells responded with enhanced LH secretion to GnRH stimulation. When steroid pretreatment was performed the responsiveness of gonadotrophs to low concentrations of GnRH was still increased. In contrast, at high concentrations of GnRH the sensitizing action of PACAP on agonist-induced LH secretion was lost in steroid-treated cells. There were no significant differences between the steroid treatment paradigms. It is concluded that estradiol but not progesterone acts as a modulator of adenylyl cyclase in gonadotrophs. The stimulatory effect of estradiol is thought to be involved in its sensitizing action on agonist-induced LH secretion. The inhibitory effect of estradiol on PACAP-stimulated adenylyl cyclase activities seems to be responsible for the loss of its action to sensitize LH secretory responses to GnRH.