deiodination การใช้

• The primary pathway of thyroid hormone metabolism is through sequential deiodination.
• Iodotyrosine deiodinase salvages the iodide from the deiodination of the iodinated tyrosines.
• Deiodination is controlled by numerous hormones and nerval signals including TSH, vasopressin and catecholamines.
• Measuring deiodination in cell culture delivers little, if any, information on total deiodination activity.
• Measuring deiodination in cell culture delivers little, if any, information on total deiodination activity.
• Whole body deiodination activity can be assessed by measuring production of radioactive iodine after loading the organism with marked thyroxine.
• "In vivo ", deiodination activity is estimated from equilibrium levels of free T 3 and free T 4.
• Deiodination capacity proved to be an inpedendent predictor of substitution dose in a trial with over 300 patients on replacement therapy with levothyroxine.
• Iodotyrosine deiodinase facilitates iodide salvage in the thyroid by catalyzing deiodination of mono-and diiodotyrosine, the halogenated byproducts of thyroid hormone production.
• The major portion of T3, however, is produced in peripheral organs, e . g . liver, adipose tissue, glia and skeletal muscle by deiodination from circulating T4.
• In addition to deiodination, thyroid hormones are also excreted through the kidneys and metabolized through conjugation and glucuronidation and excreted directly into the bile and the gut where they undergo enterohepatic recirculation.
• "In vitro ", including cell culture experiments, deiodination activity is determined by incubating cells or homogenates with high amounts of labeled thyroxine ( T 4 ) and required cosubstrates.
• Additionally, it is not possible to differentiate step-up reactions resulting in T3 production from the step-down reaction catalyzed by type 3 deiodination, which mediates production of reverse T3.
• As a measure of deiodination, the production of radioactive iodine and other physiological metabolites, in particular T 3 or reverse T 3, are determined and expressed ( e . g . as fmol / mg protein / minute ).
• It activates thyroid hormone by converting the prohormone thyroxine ( T 4 ) by outer ring deiodination ( ORD ) to bioactive thyroid, and may contribute significantly to the relative increase in thyroidal T 3 production in patients with Graves'disease and thyroid adenomas.
• It catalyzes the inactivation of thyroid hormone by inner ring deiodination of the prohormone thyroxine ( T 4 ) and the bioactive hormone 3, 3', 5'- triiodothyronine ( RT 3 ) and 3, 3'- diiodothyronine ( T 2 ), respectively.