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At least 127 records · Page 7Linked to original sources

Thyroid gland clonality revisited: the embryonal patch size of the normal human thyroid gland is very large, suggesting X-chromosome inactivation tumor clonality studies of thyroid tumors have to be interpreted with caution.

It is widely assumed thyroid carcinomas, adenomas, and many hyperplastic nodules are monoclonal. This belief is based on X-chromosome inactivation analyses of thyroid tumors. However, X-chromosome inactivation studies of tumors are informative only when interpreted in the context of the clonal composition of the surrounding normal tissue, and in the case of thyroid tissue, such analyses have never been systematically performed in humans. The aim of this study was to determine the embryonal patch size of the human thyroid gland. We performed human androgen receptor (HUMARA) assay-based X-chromosome inactivation analysis on 20 microdissected normal thyroid specimens from 16 female subjects. Monoclonality was observed in 70% of tested specimens, and polyclonal X-inactivation patterns were present in only 30% of specimens. According to our results the monoclonal patch size of normal human thyroid tissue is between 48 mm(2) and 128 mm(2) (1-4 x 10(5) thyrocytes). Our data indicate that normal thyroid epithelium is organized into large stem cell-derived monoclonal patches. Therefore, monoclonality in neoplastic and hyperplastic lesions may just be a reflection of normal thyroid epithelium clonal composition.

Adult↗

Imaging of the thyroid gland.

The thyroid gland is critical in regulating metabolic functions including cardiac rate and output, lipid catabolism, skeletal growth, and oxygen and heat production. Thus, patients with hormonally active thyroid abnormalities present with wide-ranging symptoms, requiring an understanding of the gland's hormonal functions. Radiological imaging assesses the pathophysiological affects of abnormal thyroid function as well as important morphological features. Nuclear scintigraphy provides functional information about the gland, whereas cross-sectional imaging-including ultrasound, CT, and MR-provide adjunctive anatomic information. These modalities also provide information about related structures in the neck. The embryology, anatomy, and physiology of the thyroid are discussed; congenital, autoimmune, inflammatory, metabolic, and neoplastic diseases are reviewed; and the diagnostic utility of radiological imaging is addressed.

Autoimmune Diseases↗

Occurrence of gamma-trace in the calcitonin-producing C-cells of simian thyroid gland and human medullary thyroid carcinoma.

gamma-Trace, a microprotein occurring in neuroendocrine cells, was demonstrated by immunohistochemical technique to be present in the calcitonin-producing C-cells of normal simian thyroid gland and of human medullary thyroid carcinoma. A comparatively high concentration of gamma-trace was demonstrated in tissue extract of neoplastic C-cells. The immunoreactive protein found in the extract had a molecular weight and electrophoretic mobility characteristic for gamma-trace.

Adsorption↗

Sarcoidosis of the thyroid gland manifested initially as thyroid tumor.

A rare case of a patients with sarcoidosis of the thyroid gland, who was preoperatively diagnosed as having thyroid carcinoma and who had no other clinical features of sarcoidosis, is reported. Thyroidectomy specimen revealed numerous noncaseating, epithelioid granulomas in the thyroid tissue. Mycobacteria, fungi and foreign body material were not identified. Similar granulomas were also found in the lymph nodes and muscular tissue adjacent to the thyroid gland and parathyroid gland After the diagnosis of sarcoidosis of the thyroid, systemic examination failed to reveal any involvement in other sites, including lung, eye and skin. This case demonstrated that sarcoidosis can manifest initially as a thyroid tumor with no other evidence of disease.

Aged↗

Human thyroid phenol sulfotransferase enzymes 1A1 and 1A3: activities in normal and diseased thyroid glands, and inhibition by thyroid hormones and phytoestrogens.

Sulfation by sulfotransferase enzymes (SULTs) is an important pathway for the metabolism of thyroid hormones and phytoestrogens. Intrathyroidal SULTs may contribute to the processing of thyroid hormones for the reutilization of iodide. SULT1A1 and SULT1A3 activities were identified in normal and diseased human thyroid glands. Biochemical properties that included apparent K(m) values, thermal stabilities, and responses to inhibitors were characterized in a normal human thyroid high speed supernatant pool. Apparent K(m) values for SULT1A1 and SULT1A3 activities with the model substrates p-nitrophenol and dopamine were 0.58 +/- 0.04 and 11.3 +/- 1.3 microm, respectively. Activities of SULT1A1 and SULT1A3 determined in individual normal thyroid (n = 35), nodular goiter (n = 26), and autoimmune thyroid disease (n = 25) glands were 0.34 +/- 0.06, 0.52 +/- 0.09, and 0.82 +/- 0.19 U/mg protein for SULT1A1, respectively, and 0.22 +/- 0.04, 0.21 +/- 0.04, and 0.48 +/- 0.11 U/mg protein for SULT1A3, respectively. Both SULT activities in autoimmune thyroid disease glands were significantly higher than those in normal thyroids. Only 3,3'-diiodothyronine (3,3'-T(2)) and the phytoestrogen daidzein served as substrates for the normal thyroid SULT activities, yet each thyroid hormone and phytoestrogen tested were found to inhibit thyroid SULT1A1 and SULT1A3 activities. The preference of thyroid gland SULT activities for 3,3'-T(2) suggests that sulfation may enhance degradation of intrathyroidal 3,3'-T(2) for iodide reutilization. Inhibition of these SULT activities by the exogenous phytoestrogens daidzein and genistein, with a potential decrease in iodide reutilization, presents another mechanism through which these compounds may adversely affect human thyroid function.

Arylsulfotransferase↗

[Lugol's solution and thyroid gland activity in cattle. Determination of the total thyroxine in blood plasma as a method for evaluating thyroid gland activity].

The aim of the present investigations was to examine if an intrauterine treatment with Lugol's solution in cows influences the activity of the thyroid gland. The thyrotropin-stimulation test was used to evaluate the function of the thyroid gland. An injection of 10 I. U. thyreotropin induced within 3 hours an increase of the T4 blood concentrations which reached maximal values 9 hours after the treatment and thereafter decreased again. Thyreotropin concentrations increasing from 5 to 30 I. U. led to a dose-dependent increase of the T4 blood concentrations. The T4 values obtained by 40 i. U. thyreotropin were lower than that induced with 30 I. U. of the hormone. The T4 concentrations increased stronger and remained elevated longer in cows pretreated intrauterine with Lugol's solution than in untreated control cows. The experiments demonstrated that an intrauterine infusion of Lugol's solution may result in an increased activity of the thyroid gland.

Animals↗