Reverse Triiodothyronine
Mostrando 1-12 de 26 artigos, teses e dissertações.
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1. Thyroid hormones in full-term newborn infants with neonatal sepsis / Hormônios tireoidianos em recém-nascidos a termo com sepse neonatal
Recém-nascidos com sepse apresentam sintomas clínicos e alterações laboratoriais por tempo e gravidade variáveis. A sepse neonatal pode comprometer diversos tecidos e modificar a ação das enzimas, incluindo a desiodase tipo 1, responsável pela formação do T3 plasmático a partir do T4 nos tecidos periféricos. Além disso, em certos períodos da do
Publicado em: 2008
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2. Thyroid Hormonelike Actions of 3,3′,5′-l-Triiodothyronine and 3,3′-Diiodothyronine
l-Thyroxine is converted to 3,5,3′-l-triiodothyronine (T3) as well as to 3,3′,5′-l-triiodothyronine (reverse T3). One product of further deiodination is 3,3′-diiodothyronine (3,3′T2). The serum levels of reverse T3 and 3,3′T2 change considerably in various physiological and disease states. We previously found that reverse T3 and 3,3′T2 bind to
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3. A Radioimmunoassay for Measurement of 3,3′, 5′-Triiodothyronine (Reverse T3)
A highly specific antiserum to 3,3′,5′-triiodothyronine (reverse T3, rT3) was prepared by immunization of rabbits with D,L-rT3-human serum albumin conjugate. Of the various thyroid hormone derivatives tested, only 3,3′-diiodothyronine (3,3′-T2) cross-reacted significantly (10%) with rT3-binding sites on the antiserum, while thyroxine (T4) and triiodo
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4. Synthesis of thyroid hormone metabolites by photolysis of thyroxine and thyroxine analogs in the near UV.
Photolysis of thyroxine and its analogs in the near UV permitted synthesis in good yield of picogram to gram quantities of thyroid hormone metabolites. Preparation of the same metabolites by classical chemical synthesis requires multistep procedures. Specifically labeled metabolites of high specific activity (e.g., those carrying the label in the nonphenolic
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5. Thyroid hormone stimulation of phosphatidylcholine synthesis in cultured fetal rabbit lung.
To investigate the mechanism of thyroid hormone action on pulmonary surfactant synthesis, we characterized the effect of triiodothyronine on phosphatidylcholine synthesis in cultured fetal rabbit lung. Since glucocorticoids stimulate surfactant synthesis and reduce the incidence of Respiratory Distress Syndrome in premature infants, we also examined the inte
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6. Metabolism of reverse triiodothyronine by isolated rat hepatocytes.
Reverse triiodothyronine (rT3) is metabolized predominantly by outer ring deiodination to 3,3'-diiodothyronine (3,3'-T2) in the liver. Metabolism of rT3 and 3,3'-T2 by isolated rat hepatocytes was analyzed by Sephadex LH-20 chromatography, high performance liquid chromatography, and radioimmunoassay, with closely agreeing results. Deiodinase activity was inh
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7. l-Triiodothyronine and l-Reverse-Triiodothyronine Generation in the Human Polymorphonuclear Leukocyte
Extrathyroidal monodeiodination of l-thyroxine (T4) is the principal source of l-triiodothyronine (T3) and l-reverse-triiodothyronine (rT3) production. To define some of the cellular factors involved, we examined T3 and rT3 generation from added nonradioactive T4 in human polymorphonuclear leukocytes, using radioimmunoassays to quantify the T3 and rT3 genera
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8. Effect of amiodarone on serum triiodothyronine, reverse triiodothyronine, thyroxin, and thyrotropin. A drug influencing peripheral metabolism of thyroid hormones.
2-n-Butyl-3-(4'-diethylaminoethoxy-3',5'-diiodobenzoyl)-benzofurane (amiodarone), a drug used in arrythmias and angina pectoris, contains 75 mg of organic iodine/200 mg active substance. Four studies were performed to test its effect on thyroid hormone metabolism: (a) nine male subjects were treated with 400 mg of amiodarone for 28 days; (b) five male subjec
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9. Dietary Modification of Thyroxine Deiodination in Rat Liver is Not Mediated by Hepatic Sulfhydryls
The enzymatic deiodination of thyroxine (T4) is thiol dependent. Fasting (72 h) depresses hepatic T4 deiodination and lowers the hepatic content of nonprotein sulfhydryls (NP-SH) and reduced glutathione (GSH). It has been proposed that the fasting effect may be mediated through these alterations in hepatic sulfhydryls. To test the importance of tissue (hepat
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10. Interrelationships among thyroxine, growth hormone, and the sympathetic nervous system in the regulation of 5'-iodothyronine deiodinase in rat brown adipose tissue.
Thyroxine (T4) and reverse triiodothyronine are potent inhibitors of brown adipose T4 5'-deiodinase (BAT 5'D). This effect does not require protein synthesis and is due to an acceleration of the rate of disappearance of the enzyme. Growth hormone (GH) also inhibits BAT 5'D but by a mechanism mediated through a long-lived messenger that correlates with growth
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11. Peripheral Serum Thyroxine, Triiodothyronine and Reverse Triiodothyronine Kinetics in the Low Thyroxine State of Acute Nonthyroidal Illnesses: A NONCOMPARTMENTAL ANALYSIS
The low thyroxine (T4) state of acute critical nonthyroidal illnesses is characterized by marked decreases in serum total T4 and triiodothyronine (T3) with elevated reverse T3 (rT3) values. To better define the mechanisms responsible for these alterations, serum kinetic disappearance studies of labeled T4, T3, or rT3 were determined in 16 patients with the l
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12. Circulating 3,3', 5'-triiodothyronine (reverse T3) in the human newborn.
Serum concentrations of 3,3',5'-triiodothyronine (reverse T3 rT3), 3,3',5-triiodothyronine (T), and thyroxine (T4) were measured in cord blood and invenous blood samples obtained between 2 h and 30 days of postnatal life from healthy full-term newborn infants. The mean serum rT3 concentration of (mean plus or minus SE) 151 plus or minus 12 ng per 100 ml in 1