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Imaging of the thyroid gland
Published in Pallavi Iyer, Herbert Chen, Thyroid and Parathyroid Disorders in Children, 2020
Technetium scan (Tc99m) pertechnetate (99mTcO4–) is a radio-isotope that mimics iodine and is used for thyroid imaging. It is administered via intravenous injection and is trapped in the thyrocyte via the sodium iodide symporter in the thyroid cell. The thyroid gland is scanned 20 minutes after administration to reveal the location and size of the thyroid gland compared to the locations of the markers (Figure 2.2). This study is helpful in distinguishing between the causes of congenital hypothyroidism (sublingual thyroid gland, lingual thyroid gland, thyroid aplasia, and eutopic thyroid gland). Maternal blocking antibodies may sometimes interfere with the study and note an aplastic thyroid gland, but an ultrasound reveals a eutopic thyroid gland. This study is best performed when the TSH is elevated and thus upregulating the sodium-iodide symporter (NIS) expression (1,2).
The Iodide Transport Defect
Published in Geraldo Medeiros-Neto, John Bruton Stanbury, Inherited Disorders of the Thyroid System, 2019
Geraldo Medeiros-Neto, John Bruton Stanbury
cotransporters. Cotransporters, in turn, are classified into antiporters, or exchangers, and symporters. Antiporters translocate substrates in opposite directions and symporters drive substrates in the same direction. Thus, these carriers translocate Na+ with the simultaneous translocation of another ion, such as iodide, in the same direction, and accordingly, it is suggested that the iodide carrier is a Na+/T symporter.8 The symporter iodide carrier molecule has not been fully characterized yet.
Gastrointestinal Tract as a Major Route of Pharmaceutical Administration
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
A symporter is an integral membrane protein that is involved in the transport of many differing types of molecules across the cell membrane. The symporter works in the plasma membrane and molecules are transported across the cell membrane at the same time, and is, therefore, a type of cotransporter. The transporter is called a symporter, because the molecules will travel in the same direction in relation to each other. In this type of indirect active transport, the driving ion (usually Na+) is forced through the membrane pump in the same direction as a second molecule or ion. An example of this is the Na+/glucose transporter in which the transmembrane protein permits Na+ ions and glucose to enter the cell together. The Na+ ions flow down their concentration gradient while the glucose molecules are pumped against their concentration gradient. Eventually, the Na+ is pumped back out of the cell by the Na+/K+ ATPase. This pump is used to actively transport glucose out of the GI tract and into the circulatory system (Youn et al., 2009).
Toward a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny – part I: which parameters from human studies are most relevant for toxicological assessments?
Published in Critical Reviews in Toxicology, 2020
Ursula G. Sauer, Alex Asiimwe, Philip A. Botham, Alex Charlton, Nina Hallmark, Sylvia Jacobi, Sue Marty, Stephanie Melching-Kollmuss, Joana A. Palha, Volker Strauss, Bennard van Ravenzwaay, Gerard Swaen
A specific subsection of Appendix A is dedicated to the consequences of liver enzyme induction on thyroid hormone metabolism. This contrasts with the brief mention to other molecular initiating events leading to thyroid disruption, such as the inhibition of sodium-iodide symporter or the inhibition of thyroid peroxidase (TPO) activity, which both influence thyroid hormone synthesis (Noyes et al. 2019). Similarly, reduced serum T4 levels are the focus of Appendix A, whereas high serum T4 levels are not explicitly mentioned.
Incidence and risk factors for radioactive iodine-induced sialadenitis
Published in Acta Oto-Laryngologica, 2020
Alvaro Sánchez Barrueco, Fernando González Galán, Ignacio Alcalá Rueda, Jessica Mireya Santillán Coello, María Pilar Barrio Dorado, José Miguel Villacampa Aubá, Manuel Escanciano Escanciano, Lucía Llanos Jiménez, Ignacio Mahillo Fernández, Carlos Cenjor Español
The Na+/I− symporter (NIS) plays a major role in the side effects of therapy with radioactive iodine [3]. The radiation from radioiodine damages this plasma trasmembrane glycoprotein which is highly expressed throughout the thyroid tissue but also in the basolateral membranes of the striated ducts, yet it is weakly expressed in few intercalated and excretory duct cells within the salivary glands.
Emerging therapeutic targets for treatment of leishmaniasis
Published in Expert Opinion on Therapeutic Targets, 2018
Several transporters designated for purine acquisition include LdNT1 [334], LdNT2 [335,336], LdNT3, and LdNT4 [334]. Nucleobase/proton symporter transporters from L. major – LmaNT3 and LmaNT4 [337] – demonstrated for their important role in parasite viability inside macrophage, therefore providing clues for the necessity of targeting the salvage pathway and acquisition systems for therapeutic purpose.