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We recently described a solid phase immunoradiometric assay (IRMA) for anti-thyroglobulin and anti-thyroid microsomal antibodies. In the present study a similar IRMA for gastric parietal cell antibodies (PCA) has been developed. Samples to be tested are incubated within wells of polyvinyl microtitre plates coated with solubilized gastric microsomal antigen. After removal of unbound material, PCA is detected by adding purified 125I-anti-human IgG antibody. A good correlation was found with the results of PCA assays obtained by indirect immunofluorescence. In contrast, negative PCA by IRMA were consistently obtained in sera containing high titres of several other organ specific and non-organ specific autoantibodies. PCA determinations by IRMA were than carried out in a series of normal controls and patients with autoimmune or non-autoimmune thyroid disorders. Positive results were obtained in three of 70 (4.3%) apparently normal subjects, in 16 of 87 (18.4%) patients with Hashimoto's thyroiditis, in 10 of 48 (20.8%) with idiopathic myxoedema. in 25 of 95 (25.6%) with Graves' disease and in five of 64 (7.8%) with other non-autoimmune thyroid disorders. Preliminary results showed that quantitative measurements of PCA by IRMA could be performed using a serum containing high levels of PCA as standard reference. In conclusion, PCA may be easily and specifically detected using the same IRMA procedure previously developed for anti-thyroid antibodies. We therefore suggest that the present IRMA may be proposed as a general technique for the detection of different organ specific autoantibodies. [ABSTRACT FROM AUTHOR]

Parallel measurements of circulating anti-thyroid microsomal (anti-M) antibodies by radioassay and haemagglutinatinn were performed on subjects with or without thyroid disorders. Three quarters (75.4%) of control subjects had undetectable antibody levels (< 10 u/ml) by radioassay and only 3.1% had concentrations of &ges; 75 u/ml. Abnormally elevated levels (&ges; 75 u/ml) were found in most of the patients with Hashimoto's thyroiditis (94.1%) or idiopathic myxoedema (86.7%), in the majority (75.0%) of those with Graves' disease and only in a minority of those with other thyroid disorders. The percentage of positive sera by haemagglutination was verisimilar in all groups to that of abnormal values observed in the radioassay. Direct comparison of parallel tests on a total of 631 sera revealed a highly significant correlation (r = 0.91, P < 0.001) between the two methods, but elevated antibody titres by haemaegglutination were found in some sera with negative radioassays. All these sera were from a single patient with thyroid carcinoma associated with Hashimoto's thyroiditis and had elevated levels of anti-thyroglobulin (anti-Tg) antibodies. Evidence that such discrepancies were due to anti-Tg antibodies reacting with microsomal-bound Tg was provided by the demonstration that the haemagglutination produced by these sera could be completely inhibited by the addition of Tg. A similar inhibition was observed with two rabbit antisera to human Tg, but not with sera from patients with thyroid autoimmune disorders containing high levels of anti-microsomal anti-bodies. [ABSTRACT FROM AUTHOR]

Steroidogenesis of gonadal cells is tightly regulated by gonadotropins. However, certain polycyclic aromatic hydrocarbons, including Benzo[a]pyrene (BaP), induce reproductive toxicity. Several existing studies have considered higher than environmentally relevant concentrations of BaP on male and female steroidogenesis following long-term exposure. Also, the impact of short-term exposure to BaP on gonadotropin-stimulated cells is understudied. Therefore, we evaluated the effect of 1 nM and 1 µM BaP on luteinizing hormone/choriogonadotropin (LH/hCG)-mediated signalling in two steroidogenic cell models, i.e. the mouse tumor Leydig cell line mLTC1, and the human primary granulosa lutein cells (hGLC) post 8- and 24-h exposure. Cell signalling studies were performed by homogeneous time-resolved fluorescence (HTRF) assay, bioluminescence energy transfer (BRET) and Western blotting, while immunostainings and immunoassays were used for intracellular protein expression and steroidogenesis analyses, respectively. BaP decreased cAMP production in gonadotropin-stimulated mLTC1 interfering with Gαs activation. Therefore, decrease in gonadotropin-mediated CREB phosphorylation in mLTC1 treated with 1 μM BaP was observed, while StAR protein levels in gonadotropin-stimulated mLTC1 cells were unaffected by BaP. Further, BaP decreased LH- and hCG-mediated progesterone production in mLTC1. Contrastingly, BaP failed to mediate any change in cAMP, genes and proteins of steroidogenic machinery and steroidogenesis of gonadotropin-treated hGLC. Our results indicate that short-term exposure to BaP significantly impairs steroidogenic signalling in mLTC1 interfering with Gαs. These findings could have a significant impact on our understanding of the mechanism of reproductive toxicity by endocrine disruptors., (© 2024. The Author(s).)

Bisphenol A (BPA) is a ubiquitous, synthetic chemical proven to induce reproductive disorders in both men and women. The available studies investigated the effects of BPA on male and female steroidogenesis following long-term exposure to the compound at relatively high environmental concentrations. However, the impact of short-term exposure to BPA on reproduction is poorly studied. We evaluated if 8 and 24 h exposure to 1 nM and 1 µM BPA perturbs luteinizing hormone/choriogonadotropin (LH/hCG)-mediated signalling in two steroidogenic cell models, i.e., the mouse tumour Leydig cell line mLTC1, and human primary granulosa lutein cells (hGLC). Cell signalling studies were performed using a homogeneous time-resolved fluorescence (HTRF) assay and Western blotting, while gene expression analysis was carried out using real-time PCR. Immunostainings and an immunoassay were used for intracellular protein expression and steroidogenesis analyses, respectively. The presence of BPA leads to no significant changes in gonadotropin-induced cAMP accumulation, alongside phosphorylation of downstream molecules, such as ERK1/2, CREB and p38 MAPK, in both the cell models. BPA did not impact STARD1 , CYP11A1 and CYP19A1 gene expression in hGLC, nor Stard1 and Cyp17a1 expression in mLTC1 treated with LH/hCG. Additionally, the StAR protein expression was unchanged upon exposure to BPA. Progesterone and oestradiol levels in the culture medium, measured by hGLC, as well as the testosterone and progesterone levels in the culture medium, measured by mLTC1, did not change in the presence of BPA combined with LH/hCG. These data suggest that short-term exposure to environmental concentrations of BPA does not compromise the LH/hCG-induced steroidogenic potential of either human granulosa or mouse Leydig cells.

Serum myoglobin (Mb) concentrations have been measured by radioimmunoassay in normal subjects, in hypothyroid patients examined 20 days after withdrawal of thyroid hormone therapy ("short-term" hypothyroidism), and in untreated hypothyroids ("long-term" hypothyroidism). In "short-term" hypothyroids, serum Mb levels were significantly higher (p less than 0.01) than those observed in normal controls, although only a minority or patients showed elevated Mb levels. In "long-term" hypothyroids, serum Mb concentrations were significantly higher than that found in normal controls (p less than 0.0001) and in "short-term" hypothyroids (p less than 0.001). In "long-term" hypothyroidism a significant inverse correlation was found between serum thyroid hormones and Mb, whereas no similar correlation was observed in "short-term" hypothyroidism. The administration of progressively increasing doses of L-T4 untreated hypothyroids was followed by normalization of serum Mb, but serum TSH levels still remained elevated. These data indicate that the duration and the severity of hypothyroidism are important factors in the rise of serum Mb, and that the normalization of serum Mb is faster than that of serum TSH and requires less L-T4 than that needed for normal TSH secretion.

We recently described a solid phase immunoradiometric assay (IRMA) for anti-thyroglobulin and anti-thyroid microsomal antibodies. In the present study a similar IRMA for gastric parietal cell antibodies (PCA) has been developed. Samples to be tested are incubated within wells of polyvinyl microtitre plates coated with solubilized gastric microsomal antigen. After removal of unbound material, PCA is detected by adding purified 125I-anti-human IgG antibody. A good correlation was found with the results of PCA assays obtained by indirect immunofluorescence. In contrast, negative PCA by IRMA were consistently obtained in sera containing high titres of several other organ specific and non-organ specific autoantibodies. PCA determinations by IRMA were than carried out in a series of normal controls and patients with autoimmune or non-autoimmune thyroid disorders. Positive results were obtained in three of 70 (4.3%) apparently normal subjects, in 16 of 87 (18.4%) patients with Hashimoto's thyroiditis, in 10 of 48 (20.8%) with idiopathic myxoedema, in 25 of 95 (25.6%) with Graves' disease and in five of 64 (7.8%) with other non-autoimmune thyroid disorders. Preliminary results showed that quantitative measurements of PCA by IRMA could be performed using a serum containing high levels of PCA as standard reference. In conclusion, PCA may be easily and specifically detected using the same IRMA procedure previously developed for anti-thyroid antibodies. We therefore suggest that the present IRMA may be proposed as a general technique for the detection of different organ specific autoantibodies.

Amiodarone associated thyrotoxicosis (AAT) occurs in approximately 10% of patients treated with this iodine rich drug in areas of mild iodine deficiency. The thyroid radioactive iodine uptake (RAIU) is usually undetectable or very low in iodine-induced thyrotoxicosis. In the present study, 35 patients with AAT were evaluated. Twelve patients had no thyroid abnormalities by physical exam and all had 24-hr RAIU less than or equal to 4%. In contrast, nine of 11 patients with AAT and diffuse goiters and eight of 12 patients with AAT and nodular goiters had RAIU values greater than 8%. In patients with AAT and goiter it appears possible that the thyroid fails to adapt normally to the excess iodide load, resulting in an inappropriately high RAIU in the presence of excess plasma iodine.