Growth hormone regulates growth hormone receptor gene transcription in primary human thyroid cells

In this study the regulation of GH-receptor gene (GHR/GHBP) transcription by different concentrations of GH (0, 12.5, 25, 50, 150, 500 ng/ml) with and without variable TSH concentrations (0.5, 2, 20 mU/l) in primary human thyroid cells cultured in serum-free hormonally-defined medium was studied. The incubation time was 6 h and GHR/GHBP mRNA expression was quantitatively assessed by using PCR amplification at hourly intervals. Correlating with the GH-concentrations added a constant and significant increase of GHR/GHBP gene transcription was found. After the addition of 12.5 ng/ml GH, GHR/GHBP mRNA concentration remained constant over the incubation period of 6 h but in comparison with the experiments where no GH was added there was a significant change of GHR/GHBP mRNA expression. Following the addition of 25 ng/ml GH a slight but further increase of GHR/GHBP transcription products was seen which increased even more in the experiments where higher GH concentrations were used. These data focusing on GHR/GHBP gene transcription derived from cDNA synthesis and quantitative PCR amplification were confirmed by run-on experiments. Furthermore, cycloheximide did not affect these changes supporting the notion that GH stimulates GHR/GHBP gene transcription directly. In a second set of experiments, in combination with variable TSH levels, identical GH concentrations were used and no difference in either GHR/GHBP mRNA levels or in transcription rate (run-on experiments) could be found. In conclusion, we report data showing that primary thyroid cells express functional GH-receptors in which GH has a direct and dose dependent effect on the GHR/GHBP gene transcription. Furthermore, TSH does not a have a major impact on GHR/GHBP gene regulation.

[Goiter and nodular thyroid disease: clinical guidelines for diagnosis and treatment. (Waiting? Hormone therapy? Surgery? radioiodine?)]

Nodular thyroid disease is a common problem. We present clinical guidelines for the management of patients with thyroid nodules, multinodular goiters and thyroid cysts for use by primary physicians. In the initial evaluation ultrasonography of the thyroid and fine-needle aspiration biopsy (FNAB) is recommended. FNAB has become the cornerstone in the evaluation of solitary thyroid nodules, cysts and dominant nodules within multinodular goiters. If the procedure is done properly, it should have a false-negative rate of less than 5% and a false-positive rate of not more than 1%. Thyroid radionuclide scans are less frequently used in the initial evaluation of a nodular goiter. Surgery is the primary therapy for patients with nodular thyroid disease. Other available treatment options are radioiodine and TSH-suppression with thyroxine. The main indications for surgery in euthyroid patients with thyroid nodule or with nontoxic multinodular goiter are recently documented or suspected malignancy, compression of the trachea and esophagus, significant growth of the nodule, recurrence of a cyst after aspiration, neck discomfort and cosmetic concern.

Regulation of human growth hormone receptor gene transcription by triiodothyronine (T3)

In this study the hypothesis that triiodothyronine (T3) and growth hormone (GH) may have some direct or indirect effect on the regulation of GH-receptor/GH-binding protein (GHR/GHBP) gene transcription was tested. Different concentrations of T3 (0, 0.5, 2, 10 nmol/l) and GH (0, 10, 150 ng/ml) were added to human hepatoma (HuH7) cells cultured in serum-free hormonally-defined medium for 0, 1 and 2 h. Thereafter GHR/GHBP mRNA expression was quantitatively assessed by using PCR amplification. GH at a concentration of 10 ng/ml resulted in a significant increase of GHR/GHBP gene expression whereas a supraphysiological concentration of GH (150 ng/ml) caused a significant decrease of GHR/GHBP mRNA levels. The simultaneous addition of 0.5 nmol/l T3 to the variable concentrations of GH did not modify GHR/GHBP mRNA levels whereas the addition of 2 nmol/l up-regulated GHR/GHBP gene expression already after 1 h, an increase which was even more marked when 10 nmol/l of T3 was added. Interestingly, there was a positive correlation between the increase of GHR/GHBP mRNA levels and the T3 concentration used (r: 0.8). In addition, nuclear run-on experiments and GHBP determinations were performed which confirmed the changes in GHR/GHBP mRNA levels. Cycloheximide (10 microg/ml) did not alter transcription rate following GH addition but blocked GHR/GHBP gene transcription in T3 treated cells indicating that up-regulation of GHR/GHBP gene transcription caused by T3 requires new protein synthesis and is, therefore, dependent on indirect mechanisms. In conclusion, we present data showing that T3 on its own has a stimulatory effect on GHR/GHBP gene transcription which is indirect and additive to the GH-induced changes.

Bombesin receptor antagonists may be preferable to agonists for tumor targeting

Two bombesin analogs, Demobesin 4 and Demobesin 1, were characterized in vitro as gastrin-releasing peptide (GRP) receptor agonist and antagonist, respectively, and were compared as (99m)Tc-labeled ligands for their in vitro and in vivo tumor-targeting properties. METHODS: N(4)-[Pro(1),Tyr(4),Nle(14)]Bombesin (Demobesin 4) and N(4)-[d-Phe(6),Leu-NHEt(13),des-Met(14)]bombesin(6-14) (Demobesin 1) were characterized in vitro for their binding properties with GRP receptor autoradiography using GRP receptor-transfected HEK293 cells, PC3 cells, and human prostate cancer specimens. Their ability to modulate calcium mobilization in PC3 and transfected HEK293 cells was analyzed as well as their ability to trigger internalization of the GRP receptor in transfected HEK293 cells, as determined qualitatively by immunofluorescence microscopy and quantitatively by enzyme-linked immunosorbent assay (ELISA). Further, their internalization properties as (99m)Tc-labeled radioligands were tested in vitro in both cell lines. Finally, their biodistribution was analyzed in PC3 tumor-bearing mice. RESULTS: A comparable binding affinity with the 50% inhibitory concentration (IC(50)) in the nanomolar range was measured for Demobesin 4 and Demobesin 1 in all tested tissues. Demobesin 4 behaved as an agonist by strongly stimulating calcium mobilization and by triggering GRP receptor internalization. Demobesin 1 was ineffective in stimulating calcium mobilization and in triggering GRP receptor internalization. However, in these assays, it behaved as a competitive antagonist as it reversed completely the agonist-induced effects in both systems. (99m)Tc-Labeled Demobesin 1 was only weakly taken up by PC3 cells or GRP receptor-transfected HEK293 cells (10% and 5%, respectively, of total added radioactivity) compared with (99m)Tc-labeled Demobesin 4 (45% of total added radioactivity in both cell lines). Remarkably, the biodistribution study revealed a much more pronounced uptake at 1, 4, and 24 h after injection of (99m)Tc-labeled Demobesin 1 in vivo into PC3 tumors than (99m)Tc-labeled Demobesin 4. In vivo competition experiments demonstrated a specific uptake in PC3 tumors and in physiologic GRP receptor-expressing tissues. The tumor-to-kidney ratios were 0.7 for Demobesin 4 and 5.2 for Demobesin 1 at 4 h. CONCLUSION: This comparative in vitro/in vivo study with Demobesin 1 and Demobesin 4 indicates that GRP receptor antagonists may be superior targeting agents to GRP receptor agonists, suggesting a change of paradigm in the field of bombesin radiopharmaceuticals.

Fluctuation analysis of lung function as a predictor of long-term response to beta2-agonists

The response to beta(2)-agonists differs between asthmatics and has been linked to subsequent adverse events, even death. Possible determinants include beta(2)-adrenoceptor genotype at position 16, lung function and airway hyperresponsiveness. Fluctuation analysis provides a simple parameter alpha measuring the complex correlation properties of day-to-day peak expiratory flow. The present study investigated whether alpha predicts clinical response to beta(2)-agonist treatment, taking into account other conventional predictors. Analysis was performed on previously published twice-daily peak expiratory flow measurements in 66 asthmatic adults over three 6-month randomised order treatment periods: placebo, salbutamol and salmeterol. Multiple linear regression was used to determine the association between alpha during the placebo period and response to treatment (change in the number of days with symptoms), taking into account other predictors namely beta(2)-adrenoceptor genotype, lung function and its variability, and airway hyperresponsiveness. The current authors found that alpha measured during the placebo period considerably improved the prediction of response to salmeterol treatment, taking into account genotype, lung function or its variability, or airway hyperresponsiveness. The present study provides further evidence that response to beta(2)-agonists is related to the time correlation properties of lung function in asthma. The current authors conclude that fluctuation analysis of lung function offers a novel predictor to identify patients who may respond well or poorly to treatment.

Associations with multiple pituitary hormone deficiency in patients with an ectopic posterior pituitary gland

INTRODUCTION: The presence of an ectopic posterior pituitary gland (EPP) on magnetic resonance imaging (MRI) is associated with hypopituitarism with one or more hormone deficiencies. We aimed to identify risk factors for having multiple pituitary hormone deficiency (MPHD) compared to isolated growth hormone deficiency (IGHD) in patients with an EPP. METHODS: In 67 patients (45 male) with an EPP on MRI, the site (hypothalamic vs. stalk) and surface area (SA) [ x (maximum diameter/2) x (maximum height/2), mm(2)] of the EPP were recorded and compared in patients with IGHD and MPHD in relation to clinical characteristics. RESULTS: In MPHD (n = 32) compared to IGHD (n = 35) patients: age of presentation was younger (1.4 [0.1-10.7]vs. 4.0 [0.1-11.3] years, P = 0.005), major incidents during pregnancy were increased (47%vs. 20%, P = 0.02) as were admissions to a neonatal intensive care unit (NICU) (60%vs. 26%, P = 0.04), whilst EPP SA was lower (12.3 [2.4-34.6]vs. 25.7 [6.9-48.2] mm(2), P < 0.001). In patients with a hypothalamic (n = 56) compared to a stalk sited EPP (n = 11): prevalence of MPHD was greater (55%vs. 9%,P = 0.05) and EPP surface area was smaller (17.3 [2.4-48.2]vs. 25.3 [11.8-38.5] mm(2), P < 0.001). In regression analysis, after adjusting for age, presence of MPHD was associated with: major incidents during pregnancy (RR 6.8 [95%CI 1.2-37.7]), hypothalamic EPP site (RR 10.9 [1.0-123.9]) and small EPP SA (RR 2.5 [1.0-5.0] for tertiles of SA). CONCLUSION: In patients with an EPP, adverse antenatal events, size (small) and position (hypothalamic) of the posterior pituitary gland on MRI were associated with MPHD. These findings suggest that adverse factors during pregnancy may be important for the development of an EPP.

Anti-Müllerian hormone and inhibin B as predictors of pregnancy after treatment by in vitro fertilization/intracytoplasmic sperm injection

OBJECTIVE: To evaluate anti-Müllerian hormone (AMH) as a marker of reproductive outcome after IVF/intracytoplasmic sperm injection (ICSI). DESIGN: Longitudinal study. SETTING: University hospital. PATIENT(S): Two hundred seventy-six consecutive women undergoing IVF/ICSI. INTERVENTION(S): Ovarian stimulation, oocyte retrieval, IVF, ICSI, embryo transfer, AMH, and inhibin B determinations in serum and follicular fluid (FF). MAIN OUTCOME MEASURE(S): The AMH and inhibin B concentrations in 276 matched FF/serum pairs have been determined. Different outcome groups have been compared and set in relation to the oocyte count, morphological parameters, and steroid hormone levels. RESULT(S): The concentrations of AMH and inhibin B in both serum and FF were significantly higher in the group of women who became pregnant in the corresponding treatment cycle than in those who did not conceive. Positive correlations were observed between serum inhibin B concentrations and embryo morphology (r = 0.126, 95% confidence interval 0.026-0.284). Serum and FF AMH or inhibin B correlated positively with the oocyte count and negatively with the pretreatment cycle day 3 FSH level and the total administered gonadotropin dose. CONCLUSION(S): The AMH and inhibin B levels on the day of oocyte retrieval are correlated to reproductive outcome.

Current trends in hormone replacement therapy: perceptions and usage

OBJECTIVE: To determine whether physicians' confidence in the use of hormone replacement therapy (HRT) for climacteric symptoms has been affected by the negative media interpretation of data from landmark studies investigating HRT usage such as the Women's Health Initiative (WHI) study. METHODS: A structured questionnaire was completed via the internet by European and US gynecologists, obstetrician/gynecologists and general practitioners - all experienced in treating women with climacteric symptoms. RESULTS: Six hundred physicians completed the survey in six countries. Overall, 98% agreed that the menopause significantly affects quality of life and 97% considered that the majority/all of their patients experienced positive benefits from HRT. Most physicians (90%) believed the benefits of HRT outweigh the risks in suitable patients, and 92% would prescribe HRT for themselves/spouse/family. For treatment of atrophic vaginitis, 86% agreed that local estrogen was the most effective course of action. While 82% of participants were aware of the latest recommendations on low-dose HRT, and estrogen dose in particular, 67% cited lowering the progestogen dose as important. With regard to the recent negative media coverage on HRT, 78% of physicians felt this was unjustified. CONCLUSIONS: These results provide reassurance that health-care professionals in Europe and the US, experienced in treating women with climacteric symptoms, have not lost confidence in HRT. Despite a consensus on the importance of lowering the dose of HRT and a focus on estrogen, there remains a need to heighten prescribers' awareness on the pivotal role that a lower progestogen dose plays in optimizing the risk-benefit profile.