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C. Marcocci, A. Pinchera and E. F. Grollman

In eukaryotes cytoplasmic pH is an important determinant of many intracellular processes and has been implicated as a regulatory signal in several cellular events (Nuccitelli & Deamer 1981). The regulation of intracellular pH (pHi) largely depends on an electroneutral, amiloride-sensitive, Na+/H+ exchange in the plasma membrane (Nuccitelli & Deamer 1981). It has recently been suggested that a stimulation of Na+/H+ exchange, producing a rapid and persistent alkalinization is associated with mitogen action in vertebrate cells (Moolenar 1986).

FRTL-5 is a continuous strain of functioning rat thyroid cells, which require TSH for their growth (Ambesi-Impiombato et al. 1980). In the present study we describe an amiloride-sensitive Na+/H+ exchange system in these cells, and we show that it plays an important role in the regulation of pHi. The pHi has been measured using the equilibrium distribution of 14C-labelled 5,5-[2-14C]dimethyl - oxazolidine -2,4 - dione (DMO) (Waddel & Butler

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L Bartalena, C Marcocci and A Pinchera

Most patients with Graves' disease have some degree of ocular involvement, but only 3-5% of them develop severe ophthalmopathy (1). The reasons why only such a minority of patients with Graves' disease have severe expression of the ophthalmopathy remain to be elucidated. One possible explanation is that non-severe ophthalmopathy and severe ophthalmopathy are two different disorders with different genetic backgrounds; alternatively, they might be part of a spectrum of different conditions ranging from absent ocular involvement to most severe ophthalmopathy. In this case, external variables (i.e. environmental factors) must contribute to the nature of the expression of the disease. How important are they? How far can our intervention on environmental factors go towards reducing the risk of progression of the ophthalmopathy? In other words, to which extent, if any, is Graves' ophthalmopathy preventable? The aim of this mini-review is to address the above issues.

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C. Marcocci, G. F. Fenzi and E. F. Grollman

Abstract. TSH is a trophic factor for cultured rat thyroid cells (FRTL-5). In the present study we have investigated the mechanism by which TSH promotes cell growth and evaluated the possible role of the adenylate cyclase (AC)-cAMP system in this process. The mitogenic activity of several agents was evaluated by measuring their effect on cell number or 3H-thymidine incorporation into DNA. Forskolin and cholera toxin, two potent and specific activators of the AC, induced a dose dependent increase of 3H-thymidine incorporation. The maximal stimulation, observed at concentrations of 10 μm and 10 ng/ml, respectively, was β 80% of that obtained with optimal concentrations of TSH. A similar effect was obtained with a Graves' IgG preparation (0.2 mg/ml) able to stimulate the thyroid AC or with 3-isobutyl-l-methyl-xanthine (IBMX, 0.5 mm), a phosphodiesterase inhibitor. 8-bromo cAMP (0.5 mm), a cAMP analog, also stimulated 3H-thymidine incorporation, and its potency was ∼ 60% of that of TSH. Similar results were obtained when the mitogenic activity of these compounds was evaluated by cell number. Norepinephrine (NE, 10 μm), although devoid of AC stimulatory activity in these cells, also stimulated 3H-thymidine incorporation, but its potency was only 20–30% of that of TSH. Indomethacin (100 μm), an inhibitor of phospholipid and arachidonic acid metabolism, was able to inhibit the stimulatory effect of NE (84%), and to a lesser extent of TSH (63%) and cholera toxin, had minor effect on forskolin (24%), IBMX (16%) and Graves' IgG (8%), and no effect on 8-bromo cAMP. The results of the present study indicate that: 1) 8-bromo cAMP, as well as agents which stimulate the thyroid adenylate AC (cholera toxin, forskolin or Graves' IgG) or inhibit intracellular cAMP degradation (IBMX) promote FRTL-5 cell proliferation; 2) NE, although devoid of AC stimulatory activity in FRTL-5 cells, also stimulates 3H-thymidine incorporation; 3) indomethacin has a different inhibitory effect on stimulated 3H-thymidine incorporation. These data suggest that cAMP is involved in FRTL-5 cell proliferation, but other biochemical events, independent of the AC-cAMP system and indomethacin sensitive, are operating and may be required to achieve the full activation of the replicative machinery, as obtained with TSH.

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C. Marcocci, L. Bartalena, F. Bogazzi, M. Panicucci and A. Pinchera

Abstract. Eye disease was associated with hyperthyroidism in 202 of 221 patients with active Graves' ophthalmopathy (91.4%) and was not accompanied by thyroid hyperfunction (euthyroid Graves' disease) in the remaining 19 (8.6%). All the latter patients had some mild thyroid abnormalities (thyroid autoantibodies, negative TRH test, negative T3 suppression test, goitre). Sex distribution analysis evidenced a higher prevalence in females with a female/male ratio of 2.1 which was, however, significantly lower (P < 0.05) than that observed in control (Graves' disease patients without overt ophthalmopathy (female/male ratio = 3.4)). Patients with euthyroid Graves' disease showed a female/male ratio of 0.7. Age distribution revealed a peak prevalence in the 5th decade of life, identical to that of Graves' disease without ophthalmopathy. A close temporal relationship between the onset of hyperthyroidism and the onset of ophthalmopathy was found, since in about 85% of the patients the first ocular manifestations occurred within ±18 months around the onset of hyperthyroidism.

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F Cetani, E Pardi, L Cianferotti, E Vignali, A Picone, P Miccoli, A Pinchera and C Marcocci

OBJECTIVE: To report a new mutation of the multiple endocrine neoplasia type 1 (MEN1) gene in an Italian kindred. DESIGN: The study included the female proband, aged 50 years, affected by primary hyperparathyroidism, insulinoma and prolactinoma, and ten relatives. Blood samples were obtained for biochemical and genetic analyses. Clinical screening tests included serum glucose, ionized calcium, intact parathyroid hormone, GH, insulin and prolactin. The coding sequence, including nine coding exons and 16 splice sites, was amplified by PCR and directly sequenced. RESULTS: Two additional cases of primary hyperparathyroidism were identified among the paternal family members. The sequence analysis showed a heterozygous T to C transition at codon 444 in exon 9, resulting in a leucine to proline substitution (L444P) in the patient and in the two paternal family members with primary hyperparathyroidism. The L444P amino acid change was absent in 50 normal subjects. The mutation determined the loss of a BlnI restriction site of the wild-type sequence and the creation of a new restriction EcoRII site. The patient, but not her paternal affected relatives, also had a common heterozygous polymorphism (D418D) in exon 9. CONCLUSIONS: A new MEN1 mutation (L444P) in exon 9 has been identified; this substitution caused the loss of a BlnI restriction site and the creation of a new EcoRII site.

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P Agretti, L Chiovato, G De Marco, C Marcocci, B Mazzi, S Sellari-Franceschini, P Vitti, A Pinchera and M Tonacchera

OBJECTIVE: The TSH receptor (TSHr) expressed on thyroid follicular cells is the autoantigen involved in the pathogenesis of Graves' hyperthyroidism. Whether this receptor is expressed in extrathyroidal tissues, and whether it participates directly in the pathogenesis of thyroid-associated ophthalmopathy (TAO) is unclear. DESIGN: The aim of the present study was to measure TSHr mRNA in retro-orbital tissues, retro-orbital adipose tissue, extraocular muscle, and skin from patients with TAO and in several tissues from patients not affected by thyroid diseases using RT-PCR and real-time PCR. METHODS: Total RNA was isolated from tissue specimens, reverse transcribed, and amplified using specific primers for the extracellular portion and a part of a 1.3 kbp variant form of the TSHr gene. Determination of TSHr mRNA levels using real-time PCR was also performed by the TaqMan system; to normalize for differences in the amount of total RNA added to the reaction, amplification of beta-actin gene was performed as an endogenous control. RESULTS: A single-round RT-PCR amplification using specific primers for the extracellular portion of the TSHr gene demonstrated an amplification product of 1.2 kbp in the thyroid, but not in all other tissues. A second-round RT-PCR amplification using the same primers and starting from the previous amplification product demonstrated a band of the size expected for the TSHr gene in all tissue specimens analyzed irrespective of their origin. Similar results were obtained using primers specific for a part of the variant form of 1.3 kbp of the TSHr gene. The amount of TSHr mRNA measured by real-time PCR with the TaqMan probe and expressed as TSHr/beta-actin ratio was similar in the tissues from TAO patients with respect to the tissues from subjects not affected by thyroid diseases. CONCLUSIONS: We measured TSHr mRNA in tissues from patients with TAO using the very sensitive and quantitative method of real-time PCR. The level of transcription was similar to that measured in extraorbital tissues from patients who were not affected by thyroid diseases. These data suggest an illegitimate TSHr mRNA transcription in all the tissues examined apart from thyroid.

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F Cetani, E Pardi, S Borsari, E Vignali, G Dipollina, V Braga, S Adami, A Pinchera and C Marcocci

OBJECTIVE: Calcium-sensing receptor (CaR) is a candidate gene for osteoporosis susceptibility. Several CaR polymorphisms have been identified and an association between the A986S genotype and serum calcium levels has been found in Canadian postmenopausal women. We investigated whether the presence of 986S allele was associated with bone mineral density (BMD) and osteoporotic fractures. DESIGN: The study group consisted of 164 Italian postmenopausal women without fragility fracture (Fx(-)) and 55 women with fracture (Fx(+)). METHODS: A fragment of exon 7 of CaR gene containing three polymorphisms (A986S, R990G and Q1011E) was amplified by PCR and sequenced. Anthropometric characteristics and BMD were evaluated. RESULTS: The A986S polymorphism was the most commonly observed (27.9%), whereas the other two CaR polymorphisms, R990G and Q1011E, occurred in a minority of cases (8.8 and 5.5% respectively). There was no significant difference in the frequency distribution of any CaR allele between Fx(-) and Fx(+) patients. Body mass index was found to predict BMD at the lumbar spine and femoral neck. The A986S polymorphism and Years since menopause were not independent predictors of BMD at any site. As far as fracture occurrence, there was no statistically significant difference in the prevalence of fractures between women carrying or not carrying the 986S allele. CONCLUSIONS: Our data do not support a role of A986S CaR polymorphism in BMD and in the prevalence of fragility fractures in Italian postmenopausal women.

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E Macchia, M Gurnell, M Agostini, G Giorgilli, C Marcocci, TM Valenti, E Martino, KK Chatterjee and A Pinchera

We have investigated an Italian family with generalized resistance to thyroid hormone (RTH), consisting of two individuals with elevated serum thyroid hormones (TH) and a non-suppressed TSH, together with unaffected family members, for a mutation in the thyroid hormone receptor beta gene (hTR beta). We have identified a single nucleotide substitution (1321 CTT to GTT) corresponding to a leucine to valine substitution at codon 346 (L346V) in the predicted protein. The index case and her affected child are heterozygous for the receptor defect, with normal sequence in unaffected family members. Furthermore, both parents of the index case were unaffected, suggesting that the mutation had arisen de novo. When expressed in vitro, the L346V mutant receptor showed a marked reduction in its affinity for tri-iodothyronine (T3), impaired ligand-dependent transactivation and potent dominant negative activity. Its functional impairment could not be alleviated, even at supraphysiological concentrations of T3, suggesting that the mutation might interfere with the intrinsic ligand-dependent transactivation function (AF-2) located in the hormone binding domain of hTR beta. Finally, the presence of the L346V mutation in the son of the propositus, who died from complications associated with congenital heart disease, raises the possibility that RTH might have contributed to the pathogenesis or severity of the latter.

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E Vignali, A Picone, G Materazzi, S Steffe, P Berti, L Cianferotti, F Cetani, E Ambrogini, P Miccoli, A Pinchera and C Marcocci

OBJECTIVE: The traditional surgical approach for patients with primary hyperparathyroidism (PHPT) consists of the identification of at least four glands and in the removal of all hyperfunctioning parathyroid tissue. DESIGN: To evaluate whether intraoperative parathyroid hormone (PTH) monitoring will allow a more limited surgical procedure by confirming complete removal of all hyperfunctioning tissue. METHODS: Plasma samples were obtained from 206 consecutive patients with sporadic PHPT before skin incision, during manipulation of a suspected adenoma, and 5 min (T-5) and 10 min after removal of abnormal parathyroid tissue. PTH was measured by a quick immunochemiluminescent assay (QPTH). The operative success was defined by a decrease of PTH greater than 50% of the highest pre-excision value. RESULTS: A >50% decrease of PTH occurred in 203 patients and was evident at T-5 in the majority of cases. All but three had normal serum calcium the day after surgery and afterwards. PTH concentration did not show a >50% decrease in the remaining three cases after completion of surgery. One patients had negative neck exploration and remained hypercalcemic; the other two had normal serum calcium at follow-up. Thus, the intraoperative QPTH correctly predicted the outcome of surgery in 201 patients (97.5%) (200 true positive and 1 true negative), and provided three false positive and two false negative results. CONCLUSIONS: The intraoperative QPTH measurement represents a useful tool to assist the surgeon during parathyroidectomy. It indicates whether all hyperfunctioning parathyroid tissue has been removed, limiting the procedure to a unilateral neck exploration in most cases.

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C Marcocci, S Mazzeo, G Bruno-Bossio, A Picone, E Vignali, M Ciampi, P Viacava, AG Naccarato, P Miccoli, P Iacconi and A Pinchera

OBJECTIVE: To determine the usefulness of parathyroid hormone (PTH) measurement in needle aspirates of a suspicious neck mass to confirm its parathyroid nature in patients with primary hyperparathyroidism. METHODS: Thirty-three patients with surgically proved primary hyperparathyroidism were submitted to neck ultrasound (US), parathyroid scintigraphy, and assay of PTH in the aspirate (PTHa) of the suspicious cervical mass. RESULTS: Based on the results of neck US and parathyroid scintigraphy, patients were divided into two groups. Group 1: 16 patients (seven with nodular goiter) with concordant positive US and scintigraphic results. In all but one patient, PTHa was detectable and often markedly elevated (> 1000 pg in 12 patients, between 292 pg and 803 pg in three patients and 53 pg in one patient). The patient with undetectable PTHa had a small lower left parathyroid adenoma (8x8x10 mm). Group 2: 17 patients (12 with nodular goiter) with discordant US and scintigraphic results. PTHa established the parathyroid nature of the mass in 13 cases (> 1000 pg in 8 patients, between 501 pg and 953 pg in three patients and 90 and 79 pg in two patients): 11 of these had a suspected lesion by US examination but the scintigraphy results were negative; two had a mass that gave positive scintigraphy results but was of uncertain origin according to US: in both cases an intrathyroidal parathyroid adenoma was found. PTHa was undetectable in four cases (three with nodular goiter): all of these had equivocal US results, and three had positive scans and one a negative scan. CONCLUSIONS: Assay of PTHa is a simple method and should be useful for confirming the parathyroid nature of a cervical mass in patients with discordant or non-diagnostic US and scintigraphic results.