Screening for drugs potentially interfering with MCT8-mediated T3 transport in vitro identifies dexamethasone and some commonly used drugs as inhibitors of MCT8 activity

BACKGROUND

Monocarboxylate transporter 8 (MCT8) is the first thyroid hormone transporter that has been linked to a human disease. Besides genetic alterations other factors might impair MCT8 activity.

AIM

This study aimed at investigating whether some common drugs having a structural similarity with TH and/or whose treatment is associated with thyroid function test abnormalities, or which behave as antagonists of TH action can inhibit MCT8-mediated T₃ transport.

METHODS

[¹²⁵I]T₃ uptake and efflux were measured in COS-7 cells transiently transfected with hMCT8 before and after exposure to increasing concentrations of hydrocortisone, dexamethasone, prednisone, prednisolone, amiodarone, desethylamiodarone, dronedarone, buspirone, carbamazepine, valproic acid, and L-carnitine. The mode of inhibition was also determined.

RESULTS

Dexamethasone significantly inhibited T₃ uptake at 10 μM; hydrocortisone reduced T₃ uptake only at high concentrations, i.e. at 500 and 1000 μM; prednisone and prednisolone were devoid of inhibitory potential. Amiodarone caused a reduction of T₃ uptake by MCT8 only at the highest concentrations used (44% at 50 μM and 68% at 100 μM), and this effect was weaker than that produced by desethylamiodarone and dronedarone; buspirone resulted a potent inhibitor, reducing T₃ uptake at 0.1-10 μM. L-Carnitine inhibited T₃ uptake only at 500 mM and 1 M. Kinetic experiments revealed a noncompetitive mode of inhibition for all compounds. All drugs inhibiting T₃ uptake did not affect T₃ release.

CONCLUSION

This study shows a novel effect of some common drugs, which is inhibition of T₃ transport mediated by MCT8. Specifically, dexamethasone, buspirone, desethylamiodarone, and dronedarone behave as potent inhibitors of MCT8.

Gene expression profile in functioning and non-functioning nodules of autonomous multinodular goiter from an area of iodine deficiency: unexpected common characteristics between the two entities

PURPOSE

Toxic multinodular goiter is a heterogeneous disease associated with hyperthyroidism frequently detected in areas with deficient iodine intake, and functioning and non-functioning nodules, characterized by increased proliferation but opposite functional activity, may coexist in the same gland. To understand the distinct molecular pathology of each entity present in the same gland, the gene expression profile was evaluated by using the Affymetrix technology.

METHODS

Total RNA was extracted from nodular and healthy tissues of two patients and double-strand cDNA was synthesized. Biotinylated cRNA was obtained and, after chemical fragmentation, was hybridized on U133A and B arrays. Each array was stained and the acquired images were analyzed to obtain the expression levels of the transcripts. Both functioning and non-functioning nodules were compared versus healthy tissue of the corresponding patient.

RESULTS

About 16% of genes were modulated in functioning nodules, while in non-functioning nodules only 9% of genes were modulated with respect to the healthy tissue. In functioning nodules of both patients and up-regulation of cyclin D1 and cyclin-dependent kinase inhibitor 1 was observed, suggesting the presence of a possible feedback control of proliferation. Complement components C1s, C7 and C3 were down-regulated in both types of nodules, suggesting a silencing of the innate immune response. Cellular fibronectin precursor was up-regulated in both functioning nodules suggesting a possible increase of endothelial cells. Finally, Frizzled-1 was down-regulated only in functioning nodules, suggesting a role of Wnt signaling pathway in the proliferation and differentiation of these tumors. None of the thyroid-specific gene was deregulated in microarray analysis.

CONCLUSION

In conclusion, the main finding from our data is a similar modulation for both kinds of nodules in genes possibly implicated in thyroid growth.

Effect of aging on clinical features and metabolic complications of women with polycystic ovary syndrome

PURPOSE

To assess the distribution of clinical features and metabolic abnormalities of polycystic ovary syndrome (PCOS) women according to their age.

METHODS

Retrospective study on 602 women (mean age 23.9 ± 6.2 years), diagnosed according to International PCOS Network Guidelines criteria as having PCOS in a University-based Hospital. Anthropometric features, hormonal and metabolic parameters were measured and compared between the different age groups (group A ≤ 20 years; group B 21-30 years; group C > 30 years).

RESULTS

Patients in group A were more often hyperandrogenic, while in group C hypertension, dyslipidemia, obesity, impaired fasting glucose, and insulin resistance (IR) were more prevalent. After adjusting for BMI, age correlated positively with sex hormone-binding globulin (SHBG), IR, total- and LDL-cholesterol, and negatively with DHEAS, insulin, and free androgen index (FAI). SHBG was significantly associated with IR and atherogenic dyslipidemia, while FAI levels were linked to hypertension, independently of other factors considered. Furthermore, the regression analysis showed a stronger relationship between BMI and metabolic outcomes, regardless of age.

CONCLUSION

Polycystic ovarian syndrome (PCOS) phenotype changes with age. Clinical and biochemical hyperandrogenism are a major concern in young PCOS women, while metabolic burden tends to increase with aging. Some of the cardiovascular risk factors are dependent on FAI and SHBG levels, whereas BMI confirms its key role in the genesis of most of the metabolic sequelae in PCOS, independently of age.

Genetic interaction analysis of VEGF-A rs3025039 and VEGFR-2 rs2071559 identifies a genetic profile at higher risk to develop nodular goiter

CONTEXT

Nodular goiter in patients from areas of iodine deficiency is due to the growth of follicular and endothelial cells, involving different vascular-related growth factors in its pathogenesis.

OBJECTIVE

The aim of our study was to examine the association of known single polymorphisms of vascular endothelial growth factor-A [VEGF-A], VEGF receptor-2 [VEGFR-2] and hypoxia-inducible factor-1α [HIF-1α] genes or their genetic interactions with the risk of nodular goiter development.

PATIENTS AND METHODS

116 normal subjects, without any thyroid disease, and 108 subjects with nodular goiter [subjects with goiter and at least one thyroid nodule of > 1 cm of maximum size and in absence of signs of autoimmunity] were selected from a homogeneous population living in a mild iodine deficiency geographic area. Analyses were performed on germline DNA obtained from blood samples and VEGF-A rs3025039, VEGFR-2 rs2071559, and HIF-1αrs11549465 SNPs were investigated by real-time PCR technique. The multifactor dimensionality reduction [MDR] methodology was applied to investigate the genetic interaction between SNPs. Hardy-Weinberg equilibrium was performed.

RESULTS

None of the studied polymorphisms were individually associated with a higher risk to develop nodular goiter [P > 0.05]. The combination of the VEGF-A rs3025039 and VEGFR-2 rs2071559 polymorphisms had the highest accuracy of 0.58 [P = 0.018] and the interaction of some genotypes was significantly associated with the risk of nodular goiter development.

CONCLUSIONS

Our results support a genetic interaction between the VEGF-A rs3025039 and VEGFR-2 rs2071559 polymorphisms as a predictor of the risk to develop nodular goiter in subjects coming from an area with mild iodine deficiency.

BRAF mutation analysis in thyroid nodules with indeterminate cytology: our experience on surgical management of patients with thyroid nodules from an area of borderline iodine deficiency

PURPOSE

Fine-needle aspiration (FNA) with cytologic evaluation is the most reliable tool for malignancy prediction in thyroid nodules, but cytologic diagnosis remains indeterminate for 12-18 % of nodules. BRAF V600E mutation has been reported to show a high specificity for malignant thyroid nodules and the use of this marker to refine indeterminate FNA cytology results may be a useful diagnostic adjunctive tool in the pre-operative evaluation of thyroid nodules. The aim of this study was to estimate the prevalence of BRAF exon 15 mutation (V600E) and its clinical value as a diagnostic tool in a series of thyroid nodules with indeterminate cytology from an area of borderline iodine deficiency.

SUBJECTS AND METHODS

One hundred and fifty-three thyroid samples obtained by FNA of thyroid nodules from 151 patients were subjected to the analysis of BRAF V600E mutation by direct sequencing. In the study 54 nodules with indeterminate cytology, 56 benign and 43 malignant thyroid nodules were included.

RESULTS

V600E BRAF gene mutation was demonstrated in 19/43 malignant nodules, in 0/56 benign nodules and in only 1/54 indeterminate nodules that, after histology, turned out to be at a papillary thyroid carcinoma.

CONCLUSIONS

The application of BRAF exon 15 analysis showed limitations when applied to discriminate thyroid nodules with indeterminate cytology if wild-type BRAF is found, and there is no role for avoiding diagnostic thyroid surgery.

Frequency and effect on serum TSH of phosphodiesterase 8B (PDE8B) gene polymorphisms in patients with sporadic nonautoimmune subclinical hypothyroidism

BACKGROUND

Nonautoimmune subclinical hypothyroidism (NSH) is characterized by elevated serum TSH in presence of normal thyroid hormone levels and absence of anti-thyroid antibodies. As result of a genomic-wide study, a strong association between three polymorphic variants in intron 1 of human PDE8B gene (rs4704397, rs6885099, rs2046045) and serum TSH has been reported in euthyroid subjects.

AIM

The aim of this study was to evaluate frequency and effects on serum TSH of PDE8B gene polymorphisms in patients with sporadic NSH and verify if differences in serum TSH levels are associated to these polymorphic variants.

SUBJECTS AND METHODS

A total of 58 Italian selected patients affected by NSH, with elevated serum TSH, normal FT3 and FT4 and without TSHr gene mutations, were subjected to genotyping for specific single nucleotide polymorphism of PDE8B gene.

RESULTS

In all patients, the integrity of TSH receptor gene was attested. The ancestral allele associated with increased serum TSH was present in 42/58 patients (72.4 %) for rs4704397, in 42/58 patients (72.4 %) for rs6885099 and in 44/58 patients (75.9 %) for rs2046045. However, similar values of serum TSH were detected in patients with minor or major allele for each polymorphism.

CONCLUSIONS

A prevalence of the minor allele of PDE8B gene polymorphism associated with elevated serum levels of TSH was demonstrated in patients affected by sporadic NSH; however, significant differences in circulating TSH in patients with minor or major alleles for each polymorphism were not identified demonstrating the lack of association between the polymorphisms and serum TSH levels in these patients.

Sequencing of the entire coding region of the receptor associated protein (RAP) in patients with primary hypothyroidism of unknown origin

The LDL receptor-associated protein (RAP) is involved in secretion of thyroglobulin (Tg) from the thyrocyte to the colloid. Disruption of the RAP gene in mice results in a reduced Tg content within the colloid, leading to subclinical hypothyroidism and histological alterations resembling early goiter. Here we studied the entire coding sequence of RAP in genomic DNA samples from 18 patients with primary hypothyroidism not due to thyroid autoimmunity or dysgenesis. The control group included 21 subjects with no evidence of thyroid alterations. Eleven different polymorphisms with amino-acid substitution and 4 different missense polymorphisms without amino-acid substitution were found in various regions of the RAP gene. Only one polymorphism in exone 7 (V311M) was observed exclusively in patients, but it had been previously reported in normal subjects as well. The remaining polymorphisms were found either both in patients and controls or only in controls and had not been previously reported. The frequency of the various polymorphisms did not differ significantly between patients and controls. Based on these findings, we conclude that alterations of the RAP gene are not a common cause of hypothyroidism, although it cannot be excluded that other, rarer alterations with a pathogenic effect exist, and that they should be investigated in a larger number of patients.

The sodium-iodide symporter expression in placental tissue at different gestational age: an immunohistochemical study

BACKGROUND

Iodide (I(-)) is crucial for foetal thyroid function. Foetal iodide results from maternal circulating iodide and from deiodination of iodothyronines within the placenta. The Na(+)/I(-) symporter (NIS) localized in placental cells appears to be involved in iodide exchange. Low NIS expression has been reported in trophoblast cells from the first trimester and pregnancy at term.

AIMS

The aim of this study was to examine NIS expression by immunohistochemistry in the major components of human ovular tissue and placenta.

MATERIALS AND METHODS

Formalin-fixed and paraffin-embedded specimens of placental tissue from the first trimester and at term were analysed. NIS expression was quantified as percentage of NIS-positive cells/total cells. NIS expression was also evaluated by real-time polymerase chain reaction (RT-PCR) in five first-trimester and five at-term placental specimens.

RESULTS

In the first-trimester specimens heterogeneous NIS immunoreactivity was found in cyto-syncytiotrophoblast cells, with a range of NIS-positive cells from 5% to 80% (mean +/- SD 21.85 +/- 23.95), in mesenchymal and endothelial cells from 1% to 40% (14.5 +/- 11.16), in decidual cells from 5% to 40% (10.38 +/- 11.98) and in endometrial glands from 3% to 40% (21.86 +/- 13.93). In specimens from placenta at term, NIS-positive cyto-syncytiotrophoblast cells were between 5% and 40% (mean 17.85 +/- 18.15), mesenchymal and endothelial cells between 1% and 40% (13.67 +/- 12.16), decidual tissue between 5% and 30% (16.43 +/- 9.08), and endometrial glands between 3% and 40% (16.67 +/- 15.27). No significant differences in NIS expression were observed between the first trimester and placenta at term. A similar level of mRNA expression for the NIS gene was obtained by RT-PCR both in ovular material of the first trimester and in placenta at term.

CONCLUSIONS

We found NIS to be expressed in various placental and ovular components and its expression to remain constant during pregnancy.

The newly developed three-dimensional (3D) and two-dimensional (2D) thyroid ultrasound are strongly correlated, but 2D overestimates thyroid volume in the presence of nodules

The newly developed three-dimensional (3D) and two-dimensional (2D) thyroid ultrasound (US) were compared in assessing thyroid volume (TV) in 104 patients: 53 had an isolated thyroid nodule, 32 toxic diffuse goiter, 17 non-toxic multinodular goiter, 1 toxic multinodular goiter and 1 a toxic adenoma. A real-time Technos apparatus (Esaote SpA, Italy) with a 7,5 MHz linear transducer was used. The volume of thyroid lobes by 2D was calculated according to the ellipsoid formula. In the same session, TV by 3D US was calculated using a probe tracking system (in vivo ScanNT Esaote 3.4 MedCom. Darmasdt) and software to reconstruct 3D images, directly giving the lobe volume. There was a very good agreement between 2D and 3D, but in 94/208 lobes with nodular lesions 2D showed a 10% systematic overestimation compared to 3D, the percentage error being higher in lobes with lower volumes. A possible explanation for this result is the inadequacy of the ellipsoid formula in forecasting the correct lobe profile in the presence of nodules. This intrinsic defect of 2D US should be taken into account when evaluating TV in patients with nodular goiter.

[Spectrophotometric evaluation of N-acetyl-beta-glucosaminidase in urine]

A spectrophotometric method for the assay of N-Acetyl-beta-Glucosaminidase activity in human undiluted urines is described. The application of this method is recommended for its sensitivity (2,6 X 10(-4)M) and its rapid performance, because it represents a good alternative to current methods and essentially to the fluorimetric technique with which it has a significant statistical correlation. Estimates of normal individuals aged between 1-70 years are reported.

[Environment microbiological control in a department with patients at great risk (author's transl)]

Microbic flora has been studied in the Centro di Rianimazione of the Ospedali Riuniti in Chieti to control validity of the antibacterial systems and to verify efficacy of the filter systems that allow the admission into the isolation boxes, stopping great bacterial exogenous increases. These inspection have been executed by suction system Batteriological Air Pollution Detector.