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At least 109 records · Page 6Linked to original sources
PubMed1997

Transient iodine organification defect in infants with ectopic thyroid glands.

BACKGROUND: Thyroid gland ectopy is the most common cause in infants with congenital hypothyroidism (CH). Its association with iodine organification defect, as suggested by positive perchlorate discharge test (PDT) has been reported. However, whether such an association represents a true or transient defect has not yet been determined. This finding has an important clinical, epidemiological, and genetic implications. OBJECTIVE: To determine the natural history of iodine organification defect in patients with CH caused by thyroid ectopy detected by neonatal screening. DESIGN: Prospective longitudinal study. SETTING: King Khalid University Hospital, Riyadh, Saudi Arabia. PATIENTS AND METHODS: PDT was performed, at the time of diagnosis and follow-up, in infants who showed an enlarged ectopic thyroid gland with a Tc-99m pertechnetate uptake of 2% or more. RESULTS: Of 115 neonates with ectopic thyroid glands, 19 showed an enlarged gland with Tc-99m uptake ranging from 2 to 3.2%. Perchlorate discharge test was performed in 13 of these and was consistent with iodine organification defect in nine. Repeated PDT in seven patients showed normal values. CONCLUSION: The results of the authors' study indicate the transient nature of the iodine organification defect and suggest that a delay in the developmental of synthetic mechanisms occur in the dysgenetic glands.

Choristoma↗
PubMed1983

Coexistent carcinoma of the thyroid gland and Hashimoto's thyroiditis.

Three instances of Hashimoto's thyroiditis occurring in association with carcinoma of the thyroid gland are presented. Diagnosis was made by open surgical biopsy, revealing one papillary, one follicular and one mixed papillary-follicular carcinoma. Total thyroidectomy was performed and TSH suppressive therapy was administered postoperatively. All patients are alive with no evidence of local recurrence or distant metastases observed during five to 13 years of follow-up study. In our series, three of 18 patients had coexistent carcinoma of the thyroid gland and Hashimoto's disease. This figure is lower than the 25 per cent incidence of carcinoma of the thyroid gland in noninflammatory goiters observed at the same hospital. Although the number of patients is small, Hashimoto's thyroiditis does not seem to be a premalignant lesion and should not be treated by total thyroidectomy. A review of the literature points out that clinical, biochemical and radioactive scan findings in patients with Hashimoto's thyroiditis do not aid in differentiating between glands with or without coexistent carcinoma of the thyroid gland unless the goiter is uninodular and cold on the radioiodine scan. The prognosis of patients with carcinoma of the thyroid gland occurring in association with Hashimoto's disease is probably better than that of patients with carcinoma of the thyroid gland alone. It seems that the presence of the chronic inflammatory reaction may suppress growth and metastatic dissemination of the coexistent neoplasm of the thyroid gland.

Adenocarcinoma↗
PubMed1980

[Effect of thyrotropic hormone on the membrane potential of thyroid gland cells and thyroid hormone secretion with aging].

Effect of thyrotropic hormone (TTH) on membrane potential (MP) of thyroid cells and thyroid hormone secretion was studied in experiments on male rats of two age groups (7--12- and 27--32-month-old animals). It was found that during the first 3 hours after TTH administration (5 U/100 g i. v.) the depolarization of secretory cell membranes of adult rats was done pronounced and developed more rapidly than in old ones and that an increase in free thyroxin (T4) correlation with MP changes with time. In a dose of 0.5 U/100 g TTH caused a significant rise in T4 secretion only in old rats. The cAMP level in the thyroid gland declined with aging. In a dose of 5 U/100 g TTH provoked a significant increase in the cAMP content in adult rats and had no effect on its content in old ones. A relationship between the MP level of thyroid secretory cells and thyroid hormone secretion is discussed.

Age Factors↗
PubMedDate not supplied

[Regulation of incorporation of amino acids into the thyroid gland proteins by thyroid hormones].

The effect of thyroid hormones and of iodide (1 x 10(-7)M, 5 x 10(-5)M) on the protein synthesis in the cell-free system made of the nodular goiter cells was investigated. As revealed, with the action of thyroid hormones the 14C-amino acids incorporation into the trichloracetic acid-precipitated proteins was considerably diminished. The greatest inhibition of the 14C-amino acids incorporation was observed in toxic (5 x 10(-5)M) hormone concentration. The inhibitory action of triiodthyronine was more expressed than that of thyroxin. Addition of potassium iodide into the incubation medium led to a slight inhibition of the labeled amino acids incorporation. The results obtained permit to regard thyroid hormones as highly specific inhibitors of protein synthesis in the thyroid gland.

Amino Acids↗
PubMed1986

Thyroid gland volume and thyroid function during and after acute hepatitis infection.

Thyroid function, the occurrence of goiter, and ultrasonically determined thyroid gland volume were investigated in 23 consecutive nonalcoholic patients with acute viral hepatitis during and six months after recovery, and compared with data obtained from 23 matched controls. Seven patients had clinically detectable goiter during disease, but only one after recovery (P less than 0.05). Median thyroid volume was 28 mL (range 15 to 42 mL) compared with 18 mL (range 12 to 27 mL) after recovery (P less than 0.001), and 17 mL (range 11 to 24 mL) in the controls (P less than 0.001). During acute hepatitis, serum levels of thyroxine, thyroxine binding globulin, and free thyroxine index were significantly increased while triiodothyronine and thyrotropin levels were unaltered and triiodothyronine resin uptake and free triiodothyronine index levels were decreased. After recovery all thyroid variables were normalized. In conclusion, acute liver disease was associated with a marked increase in thyroid volume, but the study did not clarify the mechanism underlying thyroid enlargement.

Acute Disease↗
PubMed1997

Effects of estradiol benzoate on 5'-iodothyronine deiodinase activities in female rat anterior pituitary gland, liver and thyroid gland.

There is little information on the possible effects of estrogen on the activity of 5'-deiodinase (5'-ID), an enzyme responsible for the generation of T3, the biologically active thyroid hormone. In the present study, anterior pituitary sonicates or hepatic and thyroid microsomes from ovariectomized (OVX) rats treated or not with estradiol benzoate (EB, 0.7 or 14 micrograms/100 g body weight, s.c., for 10 days) were assayed for type I 5'-ID (5'-ID-I) and type II 5'-ID (5'-ID-II, only in pituitary) activities. The 5'-ID activity was evaluated by the release of 125I from deiodinated 125I rT3, using specific assay conditions for type I or type II. Serum TSH and free T3 and free T4 were measured by radioimmunoassay. OVX alone induced a reduction in pituitary 5'-ID-I (control = 723.7 +/- 67.9 vs OVX = 413.9 +/- 26.9; P < 0.05), while the EB-treated OVX group showed activity similar to that of the normal group. Thyroid 5'-ID-I showed the same pattern of changes, but these changes were not statistically significant. Pituitary and hepatic 5'-ID-II did not show major alterations. The treatment with the higher EB dose (14 micrograms), contrary to the results obtained with the lower dose, had no effect on the reduced pituitary 5'-ID-I of OVX rats. However, it induced an important increment of 5'-ID-I in the thyroid gland (0.8 times higher than that of the normal group: control = 131.9 +/- 23.7 vs OVX + EB 14 micrograms = 248.0 +/- 31.2; P < 0.05), which is associated with increased serum TSH (0.6-fold vs OVX, P < 0.05) but normal serum free T3 and free T4. The data suggest that estrogen is a physiological stimulator of anterior pituitary 5'-ID-I and a potent stimulator of the thyroid enzyme when employed at high doses.

Analysis of Variance↗
PubMed1976

[Histochemical studies of several "K"-cell enzymes in guinea pig thyroid glands].

The thyroid gland of guinea pigs were studied morphologically. Histochemical methods were used for detection of lactate dehydrogenase, succinic dehydrogenase, cholinesterase, alkaline phosphatase and acid phosphatase. The distribution of "C"-cells in normal thyroid glands was proved to be uneven. In the center of the gland they were more numerous. For statistical investigations the method of silver impregnation of "C"-cells is more practicable, since they can not be obviously distinguished from acinar cells on the basis of glycerophosphate dehydrogenase only. The activity of cholinestarase in "C"-cells and in some other cells of folliculi epithelium is very high. A supposition is made that there exist two kinds of the follicular lining thyrocytes, having different histochemical properties and histogenesis as well.

Acid Phosphatase↗
PubMed1996

Evaluation and management of the lingual thyroid gland.

Lingual thyroid gland is a rare clinical entity that is due to failure of descent of the gland anlage early in the course of embryogenesis. It may present with symptoms of dysphagia, upper airway obstruction, or even hemorrhage at any time from infancy through adulthood. We present two illustrative cases of lingual thyroid gland along with a protocol for diagnosis and management of the condition. Elements in the diagnostic and therapeutic evaluation are described with attention to the clinical findings, laboratory tests, and radiographic imaging studies employed in confirming the diagnosis and planning appropriate treatment. The natural history of the condition is reviewed and a treatment strategy is outlined that focuses on the use of suppressive doses of thyroid hormone as the initial therapy. Surgical excision of the gland is reserved for more advanced cases of gland enlargement resulting in airway compromise, severe dysphagia that limits oral intake, or ongoing hemorrhage.

Adult↗
PubMed1980

Estimation of thyroid gland activity in the Snell dwarf mouse by ultrastructural observation of the thyroid gland, measurement of plasma thyroxine concentration and thyroid hormone binding capacity.

An ultrastructural study of the thyroid gland of the Snell dwarf mouse showed cellular activity to be very low. Follicle cell diameters were significantly lower than in controls whilst the nucleocytoplasmic ratio was significantly higher. The observed cellular activity of the thyroid cells was associated with circulating levels of thyroxine which were found to be significantly lower than in controls. Measurement of the free thyroxine index showed very little free hormone available for tissue uptake. No differences in thyroid function due to age or sex in the dwarf mice were seen. Possible endocrine imbalances contributing to the low thyroid activity in the Snell dwarf mouse are discussed.

Animals↗
PubMed2003

The stimulatory G protein alpha-subunit Gs alpha is imprinted in human thyroid glands: implications for thyroid function in pseudohypoparathyroidism types 1A and 1B.

The stimulatory G protein alpha-subunit G(s)alpha couples receptors to adenylyl cyclase and is required for hormone-stimulated cAMP generation. In Albright hereditary osteodystrophy, heterozygous G(s)alpha null mutations only lead to PTH, TSH, and gonadotropin resistance when inherited maternally [pseudohypoparathyroidism type 1A; (PHP1A)]. Maternal-specific expression of G(s)alpha in specific hormone targets could explain this observation. Using hot-stop PCR analysis on total RNA from six normal human thyroid specimens, we showed that the majority of the G(s)alpha mRNA (72 +/- 3%) was derived from the maternal allele. This is consistent with the presence of TSH resistance in patients with maternal G(s)alpha null mutations (PHP1A) and the absence of TSH resistance in patients with paternal G(s)alpha mutations (pseudopseudohypoparathyroidism). Patients with PTH resistance in the absence of Albright hereditary osteodystrophy (PHP1B) have an imprinting defect of the G(s)alpha gene resulting in both alleles having a paternal epigenotype, which would lead to a more moderate level of thyroid-specific G(s)alpha deficiency. We found evidence of borderline TSH resistance in 10 of 22 PHP1B patients. This study provides further evidence for tissue-specific imprinting of G(s)alpha in humans and provides a potential mechanism for mild to moderate TSH resistance in PHP1A and borderline resistance in some patients with PHP1B.

Alleles↗
PubMed2002

Expression of the cholecystokinin 2-receptor in normal human thyroid gland and medullary thyroid carcinoma.

OBJECTIVE: The cholecystokinin(2)-receptor (CCK(2)R) promotes secretion and cell growth induced by its ligands cholecystokinin (CCK) and gastrin. The receptor has recently been shown to be expressed in human medullary thyroid carcinomas (MTCs). The objective of this study was to analyze CCK(2)R expression in MTC samples of different tumor stages as well as in non-malignant thyroid tissues. DESIGN AND METHODS: Using RT-PCR we investigated 19 MTC samples and TT-cells (a human MTC cell line), as well as samples of normal thyroid. In addition, we performed immunohistochemistry using calcitonin- and CCK(2)R-specific antibodies on MTCs and samples of C-cell hyperplasia. RESULTS: We demonstrate for the first time that CCK(2)R is expressed not only in MTCs but in all samples of normal thyroid tissue. Using immunohistochemistry the receptor could be localized on calcitonin-secreting C-cells. The highest incidence of CCK(2)R expression in MTCs was observed in early-tumor stages, whereas CCK(2)R could not be detected in advanced or metastasized tumors. CONCLUSIONS: The expression of CCK(2)R in C-cells suggests a physiological function for gastrin and/or CCK in the regulation of calcitonin release, presumably related to bone and calcium metabolism. Moreover, these ligands might act as growth factors in MTCs. Efforts in the development of CCK(2)R scintigraphy for the detection of MTC lesions might have to consider a lower incidence of the receptor in advanced tumor stages.

Adolescent↗