Biomedical subjects

M Marinò

Publications and source records attributed to M Marinò.

28 records · Page 2Linked to original sources

PubMed1999

Megalin (gp330) is an endocytic receptor for thyroglobulin on cultured fisher rat thyroid cells.

We recently reported that megalin (gp330), an endocytic receptor found on the apical surface of thyroid cells, binds thyroglobulin (Tg) with high affinity in solid phase assays. Megalin-bound Tg was releasable by heparin. Here we show that Fisher rat thyroid (FRTL-5) cells, a differentiated rat thyroid cell line, can bind and endocytose Tg via megalin. We first demonstrated that FRTL-5 cells express megalin in a thyroid-stimulating hormone-dependent manner. Evidence of Tg binding to megalin on FRTL-5 cells and on an immortalized rat renal proximal tubule cell line (IRPT cells), was obtained by incubating the cells with 125I-Tg, followed by chemical cross-linking and immunoprecipitation of 125I-Tg with antibodies against megalin. To investigate cell binding further, we developed an assay in which cells were incubated with unlabeled Tg at 4 degrees C, followed by incubation with heparin, which released almost all of the cell-bound Tg into the medium. In solid phase experiments designed to illuminate the mechanism of heparin release, we demonstrated that Tg is a heparin-binding protein, as are several megalin ligands. The amount of Tg released by heparin from FRTL-5 and IRPT cells, measured by enzyme-linked immunosorbent assay (ELISA), was markedly reduced by two megalin competitors, receptor-associated protein (RAP) and 1H2 (monoclonal antibody against megalin), indicating that much of the Tg released by heparin had been bound to megalin ( approximately 60-80%). The amount inhibited by RAP was considered to represent specific binding to megalin, which was saturable and of high affinity (Kd approximately 11.2 nM). Tg endocytosis by FRTL-5 and IRPT cells was demonstrated in experiments in which cells were incubated with unlabeled Tg at 37 degrees C, followed by heparin to remove cell-bound Tg. The amount of Tg internalized (measured by ELISA in the cell lysates) was reduced by RAP and 1H2, indicating that Tg endocytosis is partially mediated by megalin.

Animals↗

PubMed1999

Circulating thyroid autoantibodies in a sample of Italian octo-nonagenarians: relationship to age, sex, disability, and lipid profile.

Circulating thyroid autoantibodies were assessed in a sample of Italian octo-nonagenarians living in a restricted area (Val Vibrata, Abruzzo), and selected according to the absence or presence of chronic illness and disability. The study groups included: Group A ("Successful aging"), 98 free-living healthy, fully independent, octo-nonagenarians (57 males and 41 females, average age +/-SD 83.9+/-3 years); Group B ("Unsuccessful aging"), 62 highly disabled octo-nonagenarians (24 males and 38 females; average age 86.5+/-3.4 years), and Group C (Controls), 91 randomly selected healthy adult controls (42 males and 49 females; age 53.7+/-16.6 SD years, range 20-70). Serum autoantibodies to thyroglobulin (anti-Tg) and to thyroid peroxidase (anti-TPO) were measured by passive hemagglutination and radioimmunoassays (RIA); serum free thyroxine and thyrotropin by RIA. The prevalence of positive thyroid autoantibody tests was not significantly increased in the elderly groups compared to the controls, with the remarkable exception of anti-Tg detected by RIA which were increased in disabled elderly, compared to free-living elderly and controls. Two/62 disabled elderly had subclinical (1) or mild (1) primary hypothyroidism, and one free-living woman aged 90 years was hyperthyroid (toxic nodular goiter). No correlation was found between serum thyroid autoantibodies, thyroid hormones and TSH and serum lipoprotein fractions. The higher prevalence of thyroid autoantibodies found only in disabled, but not in free-living Italian octo-nonagenarians suggests that thyroid autoimmune phenomena in the elderly may be an expression of age-associated disease rather than related to the aging process in itself.

Aged↗

PubMed1999

Serum antibodies against megalin (GP330) in patients with autoimmune thyroiditis.

Megalin (gp330) is a multiligand receptor found on the apical surface of selected epithelial cells, including thyroid cells. We recently showed that megalin is a high-affinity receptor for thyroglobulin. Megalin is capable of inducing autoantibodies, as shown in the rat model, Heymann nephritis. Based on this consideration and on the knowledge that autoantibodies against several thyroid antigens develop in patients with autoimmune thyroid diseases, we searched for antimegalin antibodies in 78 patients with autoimmune and nonautoimmune thyroid diseases. We developed an assay, based on flow cytometry, to measure binding of serum IgGs to L2 cells, a rat carcinoma cell line that expresses abundant megalin. After incubation of L2 cells with serum samples and then with fluorescein isothiocynate-conjugated antihuman IgG Fc-specific antibody, the mean fluorescence intensity (MFI) was determined. Using results obtained in sera from 32 normal subjects, we established a cutoff value for MFI (50.62), above which, tests were considered positive. Significantly elevated values were found in 18 patients, including 13 of 26 patients with autoimmune thyroiditis (50.0%) and in 2 of 19 patients with Graves' disease (10.5%). Furthermore, 2 of 19 patients with nontoxic goiter (10.5%) and 1 of 14 patients with differentiated thyroid cancer (7.14%) had MFI values greater than 50.62, associated with the presence of circulating antithyroid autoantibodies. As a control cell line, we used Chinese hamster ovary cells, which do not express megalin. We found that, among the 18 patients with positive tests for binding to L2 cells, only 1 patient with nontoxic goiter had significant binding of serum IgGs to Chinese hamster ovary cells. Binding of serum IgGs to L2 cells was significantly reduced by coincubation with purified megalin in 15 of 18 positive patients (83.33%) and by a rabbit antimegalin antibody in 11 patients (61.11%). Further and more conclusive evidence that positive tests (MFI >50.62) for binding to L2 cells were attributable to serum antimegalin antibodies was demonstrated by immunoprecipitation experiments. After incubation of serum samples with L2 cell extracts, incubation with antihuman IgG Fc-specific agarose beads resulted in immunoprecipitation of megalin in all the 18 positive patients, but not in normal subjects, as assessed by Western blotting using a monoclonal antibody against megalin. Furthermore, the intensity of the band corresponding to megalin precipitated by serum IgGs in the above 18 patients was significantly correlated with the L2 binding MFI. This is the first clear-cut demonstration of antibodies against megalin in humans. Further studies are needed to determine whether antimegalin antibodies have pathogenic significance or diagnostic value in autoimmune thyroid diseases.

Adult↗

PubMed1998

Chronic recurrent stress due to panic disorder does not precipitate Graves' disease.

A role of psychic stress in precipitating hyperthyroid Graves' disease has been suggested, but the evidence in support of this pathogenetic mechanism is conflicting. In this study we investigated the possible occurrence of Graves' disease in patients with panic disorder, a psychiatric condition characterized by recurrent endogenous stress. The study group included 87 consecutive patients suffering from panic disorder since 1 to 30 years: 17 males (mean age 31.3, range 26-43 years) and 70 females (mean age 37.6, range 15-73 years). Two hundred and sixty-two normal subjects with no present or past history of psychiatric disorder served as controls. Patients were submitted to a full evaluation of the thyroid that included physical examination, assays for free thyroid hormones, TSH, thyroglobulin (TgAb), thyroperoxidase (TPOAb) and TSH receptor (TRAb) antibodies, and thyroid echography. The prevalence of circulating TgAb and/or TPOAb in patients with panic disorder did not differ from that in the control group. Twelve patients with panic disorder (13.7%) had circulating TgAb and/or TPOAb, but none had TRAb. Three out of 12 patients with thyroid antibodies, indicating a genetic susceptibility to autoimmune thyroid disease, had a family history of clinical thyroid autoimmunity, and 4 of them had a hypoechogenic pattern of the thyroid at ultrasound suggesting autoimmune thyroiditis. None of the patients with panic disorder had a previous history of hyperthyroidism. On examination, clinical hyperthyroidism or endocrine ophthalmopathy were not found in any of them. A small goiter was appreciated by palpation in 16 patients (18.3%). Free thyroid hormones and TSH were within the normal range in all patients but one: a 55-year old lady with normal serum free thyroid hormones and undetectable TSH. During an 18-month follow-up she did not develop hyperthyroidism and her TSH spontaneously returned in the normal range. Considering the individual duration of panic disorder, evidence for previous or present Graves' hyperthyroidism was not found for a total of 478 patient-years of exposure to recurrent endogenous stress in the whole study group, and for a total of 39 patient-years in patients with a genetic susceptibility to autoimmune thyroid disease. In conclusion, we found that recurrent endogenous stress did not precipitate Graves' hyperthyroidism in a series of 87 patients with panic disorder, encompassing a total of 478 patient-years of exposure to stress. Failure to activate the hypothalamic-pituitary-adrenal axis by endogenous stress due to panic disorder as opposed to exogenous stress due to life-events might explain why panic disorder does not precipitate Graves' hyperthyroidism.

Adolescent↗

PubMed1997

Influences of thyroid diseases in diabetic pregnant women.

Thyroid disorders are particularly frequent in women and, second to diabetes mellitus, are the most common endocrine diseases during pregnancy. An association between insulin-dependent diabetes mellitus and thyroid autoimmunity has long been recognized. Management of thyroid diseases in pregnancy is different than in non pregnant women, due to physiological changes of thyroid hormone economy in the childbearing period. Thyroid dysfunction may affect carbohydrate metabolism and worsen glucose control in diabetic patients. On the other hand, poorly compensated diabetes mellitus may cause alteration in the production and metabolism of thyroid hormones. Pregnant women with insulin-dependent diabetes mellitus have an increased risk of developing post partum thyroiditis. These observations have lead to the recommendation that thyroid function should be checked in diabetic women during pregnancy and in the post partum.

Adult↗

PubMed1994

Serum soluble interleukin 2 (IL-2) receptor (sIL-2R) in differentiated thyroid carcinoma.

Increased concentrations of serum soluble interleukin-2 (IL-2) receptor (sIL-2R), a marker of T-lymphocyte activation, have been found in several metastatic solid tumors. To our knowledge, no information is available on serum sIL-2R in differentiated thyroid carcinoma (DTC). Aim of this study was to evaluate whether disease activity and/or thyroid status may affect circulating sIL-2R in DTC, since it is has recently been demonstrated that serum thyroid hormone concentration positively modulates circulating sIL-2R. DTC patients were divided into 3 groups: Group A: 48 patients without metastases or local recurrences; Group B: 16 patients with cervical lymph node metastases; Group C: 22 patients with distant metastases. All patients were evaluated after total thyroidectomy both off and on L-thyroxine (L-T4) therapy. Control group was composed by 20 healthy euthyroid subjects. sIL-2R was assayed by solid-phase ELISA. In the hypothyroid state, sIL-2R levels of Group A were significantly lower when compared to normal controls (256 +/- 130 vs. 461 +/- 186 U/ml, p < 0.001 by Student t test); Group B and Group C patients off L-T4 therapy had sIL-2R concentrations significantly higher (479 +/- 407 U/ml, Group B; 519 +/- 746 U/ml, Group C) when compared to hypothyroid patients of Group A (p < 0.01 and p < 0.05, respectively), but not significantly different from normal euthyroid controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma, Follicular↗

PubMed1994

False negative results observed in anti-thyroid peroxidase autoantibody determination by competitive radioimmunoassays using monoclonal antibodies.

OBJECTIVE: Anti-thyroid peroxidase autoantibody (anti-TPO) and anti-thyroid microsomal antibody (anti-M) are strictly related, but discrepancies are sometimes observed. The aim of this study was to assess the incidence and to identify the causes of these discrepancies. DESIGN AND ANTIBODY MEASUREMENTS: Anti-M by passive hemagglutination and anti-TPO by two competitive monoclonal antibody-assisted radioimmunoassays (RIA-1 and RIA-2) were measured in 10,103 sera from 4232 subjects (663 male, 3569 female) screened for thyroid disease. RESULTS: Anti-TPO and anti-M correlated quite well (r = 0.7 and p < 0.0001 by RIA-1: r = 0.74 and p < 0.0001 by RIA-2), with discrepancies mostly limited to sera with low antibody titers. After exclusion of the latter samples, anti-TPO were detected in only 79 (1.4%) out of 5317 anti-M negative sera, but were undetectable in a more consistent proportion (130/2880 = 4.5%) of sera from patients with autoimmune thyroid disease and positive anti-M. In 61 sera of the latter group, anti-TPO was measured by a non-competitive RIA (RIA-3). Forty-one (67.7%) were positive by RIA-3, suggesting the presence of anti-TPO not competing with the monoclonal antibodies of RIA-1 and RIA-2. The remaining 20 sera had undetectable anti-TPO also by RIA-3. Nineteen (95%) of these sera had positive anti-thyroglobulin (anti-Tg) autoantibody and preincubation with thyroglobulin inhibited the agglutination reaction of anti-M tests. CONCLUSION: Anti-TPO by competitive monoclonal antibody-assisted RIA is negative in a minority of sera of patients with autoimmune thyroid disease and positive anti-M. This could be accounted for by anti-Tg producing false positives in the anti-M assay and by a subset of anti-TPO not competing with the monoclonal antibodies in the RIA. When autoimmune thyroid disease is suspected on clinical grounds, a negative anti-TPO test with a competitive RIA should be confirmed always by a non-competitive assay.

Antibodies, Monoclonal↗

PubMed1993

[Radiometabolic therapy of the autonomous thyroid nodule].

The aim of this paper is to synthetically focus on current views on the use of radioiodine for the treatment of hyperthyroidism in single autonomously functioning thyroid nodules (AFN). Radioiodine administration represents a simple and effective alternative to surgical ablation of AFN, especially in elderly patients with small nodules (< 3 cm diameter). Radioiodine is very selectively accumulated in the thyroid, where it can deliver its energy without virtually affecting any other organ. Since its first use in 1942, 131I is (as Na131I) still the radioisotope of choice, due to easy availability and to its peculiar physical characteristics. These include a short half-life (8 days) and a spectrum of radiation (mainly of the beta type) with an optimal energy delivery in the nodule and with low penetration in the surrounding tissue. The effectiveness of radioiodine administration in permanently correcting hyperthyroidism in AFN has been demonstrated in many studies and may reach 80% with a single dose administration. The optimal dose has not been completely defined, but may be empirically calculated taking into account the weight of the nodule (evaluated by scintiscan or ultrasound) and the radioiodine uptake after 24 hours. In our and in many other institutions, indications to radioiodine treatment are currently the following: age > 35-40 years, diameter of the nodule < 3 cm and/or serious general diseases contraindicating surgical treatment. The only absolute contraindication to radioiodine treatment is pregnancy, due to the possible mutagenic effects on the foetus and to the extreme sensitivity of the foetal thyroid to radioiodine after the 10th week of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Thyroid function and thyroid autoimmunity independently modulate serum concentration of soluble interleukin 2 (IL-2) receptor (sIL-2R) in thyroid diseases.

OBJECTIVE: The serum concentration of soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. Increased circulating sIL-2R has been reported in untreated Graves' disease. This finding has been interpreted as the consequence of the autoimmune activation, but recent data suggest that sIL-2R is directly correlated to thyroid state. The aim of this study was to elucidate the respective roles of autoimmunity and thyroid function in modulating serum sIL-2R. DESIGN AND PATIENTS: sIL-2R was evaluated in 20 normal euthyroid subjects and in a large series of patients with autoimmune and non-autoimmune thyroid disorders in different functional state. MEASUREMENTS: sIL-2R was assayed by a solid-phase monoclonal antibody assisted ELISA method. RESULTS: Serum sIL-2R in normals was 461 +/- 186 U/ml (mean +/- SD). Increased sIL-2R was found in 61 hyperthyroid patients with Graves' disease (1610 +/- 962 U/ml, P < 0.0001) and in 23 with toxic adenoma (1121 +/- 598 U/ml, P < 0.0001). Restoration of euthyroidism lowered to normal sIL-2R in both groups. Serum sIL-2R was higher in euthyroid Graves' disease patients with active than in those with non-active ophthalmopathy. Decreased serum sIL-2R (228 +/- 93 U/ml, P < 0.0001) was found in 30 patients hypothyroid after total thyroidectomy. Highly variable circulating sIL-2R (range 100-1456 U/ml, mean +/- SD: 379 +/- 301 U/ml) was found in 49 patients with hypothyroid Hashimoto's thyroiditis (P = NS vs normals; P < 0.02 vs post-thyroidectomy hypothyroid patients). Treatment with L-thyroxine increased sIL-2R in all thyroidectomized and in the majority of Hashimoto's thyroiditis patients. In individual Hashimoto's thyroiditis patients (mostly with increased serum sIL-2R), L-thyroxine caused a decrease of circulating sIL-2R, sIL-2R was normal in 29 patients with euthyroid Hashimoto's thyroiditis. Both in Graves' disease and in Hashimoto's thyroiditis, no correlation was found between sIL-2R and anti-thyroglobulin, anti-thyroid peroxidase and anti-thyrotrophin-receptor autoantibodies. Highly significant positive correlation between serum thyroid hormones and sIL-2R was found in all study groups. CONCLUSIONS: In thyroid disorders thyroid hormones are the main regulator of serum sIL-2R concentration. The contribution of autoimmune activation may be detected only in some patients with autoimmune hypothyroidism, while in Graves' disease the role of the immune system is masked by the hyperthyroid state.

Adolescent↗

PubMedDate not supplied

Failure to use measurement of megalin secretory components complexed with serum thyroglobulin as a tool to identify metastases after surgery in papillary thyroid cancer.

When thyroid follicles are intact, some colloidal thyroglobulin (Tg) reaches the circulation by megalin-mediated transcytosis and is to various extents complexed with megalin secretory components. In contrast, in papillary thyroid cancer (PTC), serum Tg is not complexed with megalin because it is directly secreted by tumor cells. Here we attempted to use measurement of megalin secretory components to distinguish PTC patients with thyroid remnant plus metastases from those with thyroid remnant only, after thyroidectomy and before 131I ablation. Tg values in anti-Tg antibodies (TgAb)-free sera from 5 PTC patients with thyroid remnant plus metastases and 12 PTC patients with thyroid remnant only were measured following pre-adsorption with uncoupled protein A beads or with protein A beads coupled with antimegalin antibodies. The degree of Tg pre-adsorption with antimegalin antibodies was minimal, with no substantial differences between the two groups. Thus, we concluded that measurement of megalin secretory components is unlikely to be useful to identify the origin of serum Tg in PTC patients after thyroidectomy.

Adsorption↗