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Biomedical subjects

C Marcocci

Publications and source records attributed to C Marcocci.

At least 91 records · Page 5Linked to original sources
PubMed1989

More on smoking habits and Graves' ophthalmopathy.

Since a relationship between cigarette smoking and the occurrence of Graves' ophthalmopathy has been recently postulated, we reviewed the smoking habits of 1730 women, including subjects without thyroid disease, with nontoxic goiter (NTG), toxic nodular goiter or toxic adenoma (TNG), Hashimoto's thyroiditis (HT), Graves' disease without ophthalmopathy (GD) or with ophthalmopathy (GO). The prevalence of smokers in NTG, TNG and HT was about 30%, not different from that of controls. Smokers were 47.9% in GD and 64.2% in GO groups. The latter figures were highly different from those of the other groups and also from each other. The percentage of heavy smokers was higher in patients with more severe ophthalmopathy. No clear explanation for this phenomenon can be offered. The absence of a high prevalence of smokers among patients with non-toxic goiter, nonautoimmune hyperthyroidism and Hashimoto's thyroiditis, limits the impact that smoking might have had in the pathogenesis of goiter, hyperthyroidism and autoimmune phenomena of GD and GO.

Adolescent↗
PubMed1989

Recent advances in the understanding of humoral and cellular mechanisms implicated in thyroid autoimmune disorders.

In this review new data are reported indicating that the thyroid microsomal-microvillar antigen can be identified with thyroid peroxidase (TPO). This concept derives from binding studies of monoclonal and polyclonal microsomal antibodies to TPO purified by affinity chromatography or obtained by recombinant DNA technology. Furthermore, immunofluorescence studies performed on cultured thyroid cells have shown the presence of a TPO-related antigen on the surface of the cells. The expression of the TPO antigen is modulated by TSH through the cAMP pathway. The functional activities of TSH receptor autoantibodies have also been characterized. From these studies the following conclusions can be drawn: (i) TSH receptor antibodies possess multiple biological activities, interfering or mimicking TSH actions; (ii) a good correlation is observed between stimulation of adenylate cyclase and of iodide uptake by Graves' IgG. In these IgG preparations, adenylate cyclase- and growth-stimulating activities cannot be separated; (iii) antibodies blocking the TSH-dependent AC are present in patients with autoimmune hypothyroidism; (iv) a mixture of stimulating and blocking antibodies may coexist in the same patient, whose clinical status may result from the sum of the biological activities of these antibodies. Finally, new data are reported on the identification and characterization of T cell clones infiltrating the thyroid tissue of subjects with thyroid autoimmune disorders. The majority of these clones were CD8+ cytolytic T cells with natural killer activity. These latter data may be of importance in the mechanisms of thyroid damage observed in Hashimoto's glands.

Antibody Formation↗
PubMed1989

Thyroid autoantigens and their relevance in the pathogenesis of thyroid autoimmunity.

Humoral and cellular immune responses are both involved in autoimmune disorders of the thyroid gland. In the last five years, new substantial data have been obtained on the nature and the expression of thyroid cell surface autoantigens and on the demonstration of the functional heterogeneity of autoantibodies to the thyroid stimulating hormone (TSH) receptor. In the present report, attention will be mainly focused on recent studies carried out in our laboratory. The main autoantigens so far identified include the 'microsomal' antigen, thyroglobulin and the TSH receptor. For many years the 'microsomal' antigen (M) was considered a poorly characterized constituent of the cytoplasm of the thyroid cell. In the last five years, several lines of evidence were provided indicating that M is also well represented on the surface of the follicular cell and is identical to thyroid peroxidase (TPO). The use of anti-TPO monoclonal antibodies, presently available, have confirmed this antigenic identity. Microsomal (anti-TPO) antibodies are very useful markers of autoimmune thyroid disorders and are generally present in Hashimoto's thyroiditis, idiopathic myxedema and Graves' disease. TSH receptor antibodies (TRAb) are present in the sera of patients with Graves' disease. TRAb are able to stimulate thyroid adenylate cyclase and also to mimic TSH in its thyroid growth stimulation. Thus, these antibodies may have a pathogenetic role in goiter formation and in thyroid hyperfunction in Graves' disease. TRAb were also shown to inhibit both TSH binding to its receptor and TSH-stimulated adenylate cyclase activity. Recently TRAb, which inhibited TSH-stimulated adenylate cyclase activity, were found in idiopathic myxedema patients and may be responsible for impairment of thyroid function.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantigens↗
PubMed1989

Simultaneous assay of thyroid adenylate cyclase- and growth-stimulating antibodies using FRTL-5 cells. Evidence suggesting their identity in patients with Graves' disease.

The relationship between thyroid growth-stimulating antibodies (TGSAb) and thyroid adenylate cyclase-stimulating antibodies (TSAb) in patients with Graves' disease is still a matter of controversy. To investigate this problem, we have developed an assay for the simultaneous measurement of TSAb and TGSAb using FRTL-5 cells. TSAb was detected by its ability to stimulate iodide (I-) uptake and TGSAb by the 3H-thymidine ([3H]-Tdr) incorporation assay. Thirty-four immunoglobulin G (IgG) preparations from patients with active Graves' disease were selected from a previous series in order to include both TSAb-negative IgGs (n = 9) and TSAb-positive IgGs (n = 25) by the cAMP stimulation assay, with a wide range of stimulatory activity. With one exception, the TSAb-positive IgGs produced a significant stimulation of I- uptake; 20 of them were also TGSAb-positive. The nine IgGs negative in the cAMP assay, were also negative in the I-uptake and the [3H]-Tdr incorporation assays. The majority of samples had a similar potency in the two assays and a significant positive correlation was found (r = 0.76; P less than 0.001). Two IgGs previously shown to inhibit TSH-stimulated adenylate cyclase in FRTL-5 cells produced an almost complete inhibition (80-90%) of both TSH- and Graves' IgG-stimulated I- uptake and [3H]-Tdr incorporation. In conclusion, using a simultaneous assay for thyroid growth and adenylate cyclase stimulation, TGSAb in Graves' patients were found only in TSAb-positive IgGs; both Graves' IgG-stimulated activities were inhibited by antibodies blocking the TSH-dependent adenylate cyclase stimulation. Our data strongly suggest that the same antibody may be responsible for both goitre and thyroid hyperfunction of Graves' disease.

Adenylyl Cyclases↗
PubMed1989

Studies on the occurrence of ophthalmopathy in Graves' disease.

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 less than 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.

Adolescent↗
PubMed1989

Clinical and biologic behavior of bone metastases from differentiated thyroid carcinoma.

Thirty (3.8%) of 780 patients with differentiated thyroid cancer seen between 1970 and 1987 had bone metastases. The primary tumor was follicular in 26 patients and papillary in four. Mean age at diagnosis was 61 years. The manifestation of bone metastases was the presenting symptom in 18 patients (60%). Treatment included total thyroidectomy, levothyroxine sodium therapy, and radioactive iodine treatments. Twenty-seven patients had bone metastases from the initial observation, with 44 sites involved. Of the sites, 27 (61%) were shown both on iodine 131 whole-body scan (WBS) and on x-ray film, 11 (25%) only on WBS, and six (14%) only on x-ray film. Multiple involvement was observed in 11 patients. The radiologic appearance was invariably osteolytic. Serum thyroglobulin was elevated in all patients. After radioactive iodine, no WBS+/X-ray+ metastases showed a complete response, although a sclerotic border was noted in several cases, whereas six WBS+/X-ray- lesions were no longer detectable by WBS. Treatment with radioactive iodine and bone surgery resulted in a complete cure in three patients and in a reduction of tumor mass in three. Twenty-one (70%) of the patients died of thyroid cancer after a mean survival of 86 months. Of the nine patients still alive, two are free of disease, three have a good quality of life, and four have severe disability.

Bone Neoplasms↗
PubMed1988

Studies on the mechanism responsible for thyrotropin-induced expression of microsomal/peroxidase antigen in FRTL-5 cells.

The expression of the microsomal (M) antigen on the surface and in the cytoplasm of a strain of rat thyroid cells (FRTL-5) is under the regulation of TSH. In the present report the mechanism by which TSH induces such expression was investigated with the use of human microsomal antibody-positive serum and an indirect immunofluorescence technique. Studies were also performed to ascertain whether the M antigen of FRTL-5 cells could be identified with thyroid peroxidase (TPO), as suggested by recent data obtained in human thyroid tissue. Preabsorption experiments showed that, like solubilized human thyroid microsomes, purified human TPO completely abolished the binding of microsomal antibody to FRTL-5 cells. No inhibition was obtained by preabsorption with control human tissues (placenta, liver, and spleen) or human thyroglobulin, indicating that the antigen recognized by microsomal antibody in FRTL-5 cells was TPO. After 72 h of TSH withdrawal from the culture medium the M/TPO antigen disappeared from the surface and the cytoplasm of FRTL-5 cells. Readdition of TSH (250 microU/ml) to the culture medium of cells lacking the M/TPO antigen elicited its reappearance within 24-48 h. This effect of TSH was prevented by 10 microM cycloheximide or 0.5-5 micrograms/ml actinomycin D. Two well known stimulators of the adenylate cyclase-cAMP system, cholera toxin and forskolin, mimicked TSH in inducing the reappearance of the M/TPO antigen. A similar effect was observed with use of the phosphodiesterase inhibitor isobutylmethylxanthine. Reappearance of M/TPO antigen was also produced by the cAMP analog 8-bromo-cAMP. The tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate, which stimulates thyroid cell growth through a cAMP-independent pathway, was ineffective in inducing the M/TPO antigen in FRTL-5 cells. The present data indicate that 1) thyroid peroxidase accounts for most, if not all, of the microsomal antigen of FRTL-5 cells; and 2) TSH modulates the expression of the M/TPO antigen in FRTL-5 cells by a mechanism that involves cAMP production and requires mRNA formation and subsequent protein synthesis.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Sodium/proton exchange in the maintenance of intracellular pH in FRTL-5 thyroid cells.

In the present study we describe a Na+/H+ exchange system in FRTL-5 rat thyroid cells and its role in the regulation of intracellular pH (pHi). The pHi of these cells was measured in acidic medium (pH 6.5) using the equilibrium distribution of 14C-labeled 5,5'-dimethyl-oxazolidine-2,4-dione. The estimated pHi in 10 separate experiments was 7.30 +/- 0.01 (mean +/- SE). The pHi declined to 6.87 +/- 0.02 when equimolar concentrations of choline+ replaced Na+ in the incubation medium, but was restored when cells were placed in a medium containing 50 mM Na+. The necessity for external Na+ to maintain pHi, when cells are exposed to acidic solutions, is consistent with a Na+/H+ antiport system in these cells. This is further supported by the observation that pHi decreased to 6.70 +/- 0.01 when amiloride, an inhibitor of Na+/H+ exchange, was added, and that this agent prevented the recovery of pHi in Na+-depleted cells after addition of Na+ to the medium. This report also provides additional information concerning the relationship between H+ and I- uptake and suggests that there are two I- transport systems: one that is Na+-dependent, 4,4'-diisothiocyano 2,2'-disulfonic acid stilbene-sensitive, and not associated with intracellular acidification, and the other operative at an external pH of 6.5 and associated with intracellular acidification.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1987

Increased level of thyroglobulin mRNA in a human familial goiter.

Thyroglobulin (Tg) and its specific mRNA were analyzed in the thyroid gland of two cases of familial goiter. A three-fold increase in the level of stable protein and functional Tg mRNA was found in the goiter of one of the two patients in whom a desiodase defect was demonstrated. Normal concentrations of both Tg and its mRNA were found in the other goiter in which no enzymatic defect could be shown. Our results suggest that the increase of Tg mRNA levels found in the goiter with a desiodase defect was due to a chronic stimulation of the gland by TSH.

Adolescent↗
PubMed1987

Orbital cobalt irradiation combined with retrobulbar or systemic corticosteroids for Graves' ophthalmopathy: a comparative study.

Combined therapy with systemic corticosteroids and orbital cobalt radiotherapy has been shown to be an effective treatment of severe Graves' ophthalmopathy. The potentially serious side-effects of large doses of systemic corticosteroids prompted us to evaluate the use of retrobulbar corticosteroids instead of systemic corticosteroids. Forty-four patients with active Graves' ophthalmopathy were given orbital cobalt irradiation (total dose 2000 rads) and retrobulbar methylprednisolone acetate (14 bilateral injections at 20-30 d intervals). The degree of ocular involvement and responses to treatment were evaluated by numerical scoring (ophthalmopathy index, OI) and clinical assessment. Excellent or good responses were observed in 11 out of 44 patients (25%), 24 (55%) showed slight responses, and no change was found in 9 patients (20%). The initial OI mean score was 5.9; the final score was 3.2, with a change of -2.7 (P less than 0.001). Regression or partial improvement was observed in most cases (35/44, 80%) with soft tissue changes, and in all 9 cases with sight loss due to optic neuropathy. Proptosis, corneal lesions and extra-ocular muscle involvement were less responsive, since regression or partial improvement was observed in 39% (12/31), 50% (8/16) and 31% (13/42), respectively. No major side-effects were observed. The effects of this type of therapy and those obtained by combined therapy with systemic corticosteroids and orbital radiotherapy were compared in two groups of 30 patients each, randomly assigned to either treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Orbital cobalt radiotherapy and systemic or retrobulbar corticosteroids for Graves' ophthalmopathy.

Orbital radiotherapy and corticosteroids are two well-established medical treatments for severe Graves' ophthalmopathy. In this report we analyze the results obtained by the combination of orbital radiotherapy and systemic or retrobulbar corticosteroids in patients with severe Graves' ophthalmopathy. Orbital cobalt radiotherapy was carried out by a cobalt unit, delivering a total of 2,000 rads to each eye in 10 daily doses. Systemic corticosteroid treatment was started with 70-80 mg methylprednisolone/day for 2-3 weeks with subsequent progressive reduction of the dose until discontinuation of the drug after 5-6 months. Retrobulbar corticosteroid therapy was performed by 14 bilateral injections of 40 mg methylprednisolone acetate at 20- to 30-day intervals. Results were evaluated both on clinical grounds and by numerical scoring (ophthalmopathy index, OI). Excellent or good responses were obtained in the majority of 72 patients by combined treatment with orbital cobalt radiotherapy and systemic corticosteroids. Soft tissue changes, newly developed eye muscle dysfunction and optic neuropathy showed the most beneficial effects from treatment, whereas proptosis, corneal lesions and long-standing eye muscle abnormalities responded to a lesser extent. The results of a controlled clinical trial showed that the combined treatment was more effective than the administration of systemic methylprednisolone alone. Because relevant side effects of systemic corticosteroid therapy were observed in 4 cases, the clinical validity of retrobulbar corticosteroids in substitution for systemic corticosteroids was evaluated in 44 patients. Excellent or good responses were observed in 25% of these patients, slight responses being obtained in 55% and no change in 20%.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined Modality Therapy↗
PubMed1987

Norepinephrine and thyrotropin stimulation of iodide efflux in FRTL-5 thyroid cells involves metabolites of arachidonic acid and is associated with the iodination of thyroglobulin.

Ca2+-dependent and TSH-, norepinephrine (NE)-, and A23187-induced iodide (I-) efflux from FRTL-5 rat thyroid cells is inhibited by quinacrine and trifluoroperazine, agents that inhibit phospholipase A2 activity. Furthermore, I- efflux can be stimulated by an activator of phospholipase A2 activity, melittin. Phospholipase A2 action releases arachidonic acid from phospholipids; arachidonic acid enhances I- efflux in FRTL-5 cells. Inhibitors of arachidonic acid metabolism via the lipoxygenase pathway, 5,8,11,14-eicosatetraynoic acid and nordihydroguaiaretic acid, and via the cytochrome P450-linked epoxygenase pathway, piperonyl butoxide and 2-diethylaminoethyl-2,2-diphenyl valerate, but not an inhibitor of the cyclooxygenase pathway, indomethacin, can inhibit TSH-, NE-, and A23187-induced I- efflux. TSH, NE, and arachidonic acid stimulation of I- efflux in FRTL-5 cells is associated with increased iodination of thyroglobulin, which is blocked by 10 microM 5,8,11,14-eicosatetraynoic acid and 50 microM piperonyl butoxide. The data thus suggest that TSH- and NE-induced I- efflux from FRTL-5 thyroid cells involves lipoxygenase and/or epoxygenase metabolites of arachidonic acid, released from phospholipids upon Ca2+-dependent activation of phospholipase A2. Since this process is associated with the iodination of thyroglobulin, TSH- and NE-induced I- efflux in FRTL-5 cells may represent the transport of I- from the cell into the follicular lumen in vivo.

Animals↗