Purification and properties of whale thyroid-stimulating hormone III. Properties of isolated multiple components.
(17/2714)
Properties of the four purified components of whale thyroid-stimulating hormone (TSH) have been compared. The amino acid composition shows close similarity among these components. Their hexosamine and sialic acid contents are of the same magnitude, whereas the neutral sugar composition differs somewhat from each other. The molecular weight of whale TSH determined by sedimentation equilibrium is 29,000, and no difference in molecular weight as well as in Stokes radius as determined by gel filtration has been detected among these four components. The amino acid and carbohydrate compositions of whale TSH resemble those of TSH from other species, especially those of non-primate mammalian TSH. Whale TSH contains, unlike bovine TSH but like human TSH, 1-2 residues of sialic acid as a constituent carbohydrate. (+info)
Variety of GH and TSH responses to somatostatin in perfused rat pituitaries in vitro.
(18/2714)
One male rat pituitary placed in a chamber was perifused with cyclic somatostatin (GIF) for 30 min. Either 160 nM or 1.6 muM GIF caused a decrease in the release of GH. The release of TSH was also decreased by 160 nM GIF, and paradoxically increased by 1.6 muM GIF. Increasing the dose of GIF to 16 muM resulted in an abrupt rise in the release of both GH and TSH during the perfusion; then the level of GH decreased to the nadir level followed by an elevation above the base line, while that of TSH promptly fell back toward the base line. The release of PRL was not clearly affected by 16 muM GIF. [Tyr8]-GIF did not have such stimulatory activities. These results indicate that GIF not only inhibits the release of GH and TSH, but also stimulates that of GH and TSH in this system, depending on its dose. (+info)
Iodide symporter gene expression in normal and transformed rat thyroid cells.
(19/2714)
OBJECTIVE: Decrease or loss of the Na+/I- symporter (NIS) activity profoundly affects the suitability of the use of radioiodine to detect or treat metastatic thyroid tissues. The aim of our study was to verify whether specific oncogene abnormalities were responsible for the alteration in NIS activity in thyroid cells. DESIGN AND METHODS: Expression of the NIS gene was investigated by Northern blot analysis in normal and in some oncogene-transformed cell lines with different degrees of malignancy which had lost the iodide uptake ability. RESULTS: NIS gene expression was up-regulated by TSH in a dose-dependent and time-dependent way in normal PC Cl 3 cells. The same effect was observed by activating the cAMP-dependent pathway by forskolin. Conversely, insulin and 12-O-tetradecanoylphorbol-13-acetate (TPA) showed a partial inhibitory effect on NIS gene expression. The oncogene-transformed cell lines PC v-erbA, PC HaMSV, PC v-raf, and PC E1A cells showed reduced NIS mRNA levels compared with the normal PC Cl 3 cells. Conversely, an almost complete absence of NIS gene expression was found in PC RET/PTC, PC KiMSV, PC p53(143ala), and PC PyMLV cell lines. CONCLUSIONS: Our data show that oncogene activation could play a role in affecting the iodide uptake ability in thyroid tumoral cells; different mechanisms are involved in the oncogene-dependent loss of NIS activity in transformed thyroid cells. (+info)
A female case of Kallmann's syndrome.
(20/2714)
A case of 20-year-old woman with hypogonadotropic hypogonadism and anosmia is reported, since very few female cases of Kallmann's syndrome have been reported so far in Japan. Three uncles on the father's side had no children. Height was 168 cm, and arm span 165 cm. The olfactory test revealed complete anosmia. Bone age was 13 year. Chromosome was 46 XX and normal karyotype. Basal levels of serum FSH, LH and estrogens (E1, E2 and E3) were low. Serum FSH and LH levels rose slightly only after LH-RH administration, and did not increase in clomiphene test. Plasma estrogens did not increase after daily injection of 150 IU of HMG for 3 successive days. The response of serum GH to arginine infusion was normal, while that to insulin-induced hypoglycemia was poor. (+info)
Pertechnetate scintigraphy in primary congenital hypothyroidism.
(21/2714)
Primary congenital hypothyroidism (PCH) is currently detected effectively by heel-stick screening. When elevated thyrotropin (TSH) and/or decreased T4 are found in the blood of neonates, they are recalled, values are confirmed in venous blood and thyroxine replacement therapy (TRT) is immediately instituted, thus cretinism or severe retardation is prevented. However, in a significant percentage of neonates with abnormal blood levels of T4 or TSH, the disorder is transient. To help determine the exact cause of PCH and the possibility of transient PCH, pinhole thyroid imaging is performed 30 min after an intravenous injection of 18.5 MBq (500 microCi) 99mTc-pertechnetate (TcPT). Patients with a nonvisualized gland or patients with images suggesting dyshormonogenesis are reevaluated at age 3-4 y to exclude transient PCH. METHODS: To define the role of TcPT imaging in determining the exact etiology of PCH and the possibility of its being transient, we reviewed data from 103 neonates with PCH who had scintigraphy in our laboratory between 1970 and 1996 and we correlated the results with clinical outcome. RESULTS: Four patterns of thyroid scintigrams were recognized and these determined patient classification: (a) normal in 7 patients with false-positive heel-stick screening but normal venous blood hormone levels; (b) hypoplasia-ectopia in 32 patients requiring lifelong TRT; (c) nonvisualization in 35 patients-32 with agenesis requiring lifelong TRT and 3 with fetal thyroid suppression by maternal antibodies whose TRT was discontinued at a later age; and (d) dyshormonogenesis (markedly increased TcPT concentration) in 29 patients-25 with permanent PCH requiring lifelong TRT and 4 with transient PCH in whom TRT was discontinued. Of the 25 patients with dyshormonogenesis, 12 belonged to five families with two or three siblings having the same disorder. CONCLUSION: TcPT thyroid scintigraphy in the neonate with PCH provides a more specific diagnosis, is useful for selecting patients for re-evaluation to uncover transient PCH and discontinue TRT and defines dyshormonogenesis, which is familial and requires genetic counseling. It is also cost-effective. (+info)
Reduction of thyroid hormone levels by methylsulfonyl metabolites of tetra- and pentachlorinated biphenyls in male Sprague-Dawley rats.
(22/2714)
Male Sprague-Dawley rats received four consecutive intraperitoneal (i.p.) doses of five kinds of methylsulfonyl (MeSO2) metabolites of tetra- and pentachlorinated biphenyls (tetra- and pentaCBs) to determine their effects on thyroid hormone levels. The five MeSO2 metabolites, which were the major MeSO2-PCBs detected in human milk, liver and adipose tissue were 3-MeSO2-2,2',4',5-tetraCB (3-MeSO2-CB49),3-MeSO2-2,3',4',5-tetraCB (3-MeSO2-CB70), 3-MeSO2-2,2',3',4',5-pentaCB (3-MeSO2-CB87), 3-MeSO2-2,2',4',5,5'-pentaCB (3-MeSO2-CB101), and 4-MeSO2-2,2',4',5,5'-pentaCB (4-MeSO2-CB101). All five tested MeSO2 metabolites (20 mumol/kg once daily for 4 days) reduced serum total thyroxine levels 16-40% on days 2, 3, 4, and 7 (after the last dosage). The total triiodothyronine level was reduced 37% by treatment with 3-MeSO2-CB49 at day 7, but was increased 35% and 38% by 3-MeSO2-CB70 and 4-MeSO2-CB101 at days 3 and 4, respectively. The reductions in thyroid hormone levels led to an increase in thyroid stimulating hormone (TSH) levels by 3-MeSO2-CB49, 3-MeSO2-CB87 and 3-MeSO2-CB101. A 30% increase in thyroid weight was produced by 3-MeSO2-CB101 treatment. Thus, it is likely that all five tested MeSO2 metabolites could influence thyroid hormone metabolism. The results show that the tested 3- and 4-MeSO2 metabolites of tetra- and pentaCBs reduce thyroid hormone levels in rats, suggesting that the metabolites may act as endocrine-disrupters. (+info)
Effect of lithium maintenance therapy on thyroid and parathyroid function.
(23/2714)
OBJECTIVES: To assess changes induced by lithium maintenance therapy on the incidence of thyroid, parathyroid and ion alterations. These were evaluated with respect to the duration of lithium therapy, age, sex, and family history (whether or not the patient had a first-degree relative with thyroid disease). DESIGN: Prospective study. SETTING: Affective Disorders Clinic at St. Mary's Hospital, Montreal. PATIENTS: One hundred and one patients (28 men and 73 women) with bipolar disorder receiving lithium maintenance therapy ranging from 1 year's to 32 years' duration. The control group consisted of 82 patients with no psychiatric or endocrinological diagnoses from the hospital's out-patient clinics. OUTCOME MEASURES: Laboratory analyses of calcium, magnesium and thyroid-stimulating hormone levels performed before beginning lithium therapy and at biannual follow-up. RESULTS: Hypothyroidism developed in 40 patients, excluding 8 patients who were hypothyroid at baseline. All patients having first-degree relatives affected by thyroid illness had accelerated onset of hypothyroidism (3.7 years after onset of lithium therapy) compared with patients without a family history (8.6 years after onset of lithium therapy). Women over 60 years of age were more often affected by hypothyroidism than women under 60 years of age (34.6% versus 31.9%). Magnesium levels in patients on lithium treatment were unchanged from baseline levels. After lithium treatment, calcium levels were higher than either baseline levels or control levels. Thus, lithium treatment counteracted the decrease in plasma calcium levels associated with aging. CONCLUSIONS: Familial thyroid illness is a risk factor for hypothyroidism and hypercalcemia during lithium therapy. (+info)
Mono- and plurihormonal thyrotropic pituitary adenomas: pathological, hormonal and clinical studies in 12 patients.
(24/2714)
In a series of 12 patients (eight women and four men, aged between 20 and 62 years), operated on for a pituitary adenoma shown to be thyrotropic by immunocytochemistry, we performed a retrospective and comparative analysis of clinical and biological data, tumor studies including immunocytochemistry with double labeling, and proliferation marker (proliferative cell nuclear antigen (PCNA) and Ki-67) detection, electron microscopy and culture. Our study leads us to confirm that thyrotropic tumors are rare (12 of 1174 pituitary adenomas: 1%). The main points arising were that: (1) high or normal plasma TSH associated with an increase in plasma alpha-subunit and high thyroid hormone levels is the best criterion for diagnosis; (2) the failure of TSH to respond to TRH or Werner's test is not a reliable criterion for diagnosis; (3) thyrotropic adenomas may be 'silent', without clinical signs of hyperthyroidism and with only slight increase in TSH, tri-iodothyronine and thyroxine concentrations; (4) mitoses and nuclear atypies are frequently detected in large tumors, which are invasive in more than 50% of cases - the first analysis of two proliferation markers (PCNA and Ki-67) bears out the relative aggressiveness of thyrotropic adenomas; (5) thyrotropic adenomas are frequently plurihormonal. Immunocytochemical double labeling, complemented by in vitro study, showed that thyrotropic tumor cells sometimes can or sometimes cannot cosecrete TSH, GH or prolactin. The pathological identification of monohormonal and plurihormonal adenomas seems to be supported by clinical and biological differences. (+info)