Iodide trapping

If the spent fuel is processed in a nuclear fuel reprocessing plant, the radioactive iodine species (elemental iodine and methyl iodide) trapped in the spent fuel elements ate ultimately released into dissolver off gases. The radioactive iodine may then be captured by chemisorption on molecular sieve 2eohtes containing silver (89). 

A Welsbach T-816 Ozonator purchased from the Welsbach Corporation, Philadelphia, Pennsylvania, was used. The oxygen stream was dried by passage through dry silica gel and molecular sieves and then introduced into the ozonator with the operating voltage set at 115 V., the gas pressure at 8 p.s.i.g., and the gas flow rate at 1 1. per minute. The resulting ozone flow rate was 0.00245 mole per minute, as determined by titration of a potassium iodide trap. ... 

The fluorescence lifetime of trans-4-[4-(dimethylamino-styryl]-l-methylpyridinium iodide trapped in water-containing AOT-reversed micelles has been found to be markedly influenced by R, implying a significant effect on its excited-state twisting motion [122],... 

During an investigation of the synthesis of oxazole-4-carboxylates, Shapiro reported that chlorination of amino[(phenylthio)methyl]malonate derivatives 91 with A -chlorosuccinimide (NCS), followed by treatment with Hunig s base, afforded the oxazolines 93. The oxazolines 93 were then converted to the respective oxazole-4-carboxylates 94-97 through decarbomethoxylation and elimination of thiophenoxide in the presence of methyl iodide. Methyl iodide traps the ejected thiophenoxide that would otherwise demethylate the oxazole-4-carboxylate (Scheme 8.31). " ... 

II. Agents which inhibit iodide trapping Thiocyanates, perchlorates and nitrates III. Agents which inhibit hormone release ... 

Unreacted ozone starts passing through to the potassium iodide trap toward the end of the reaction. However, it is best to continue the reaction until all the suspended phenanthrene has disappeared. This usually requires a total of 1.1-1.3 mole-equivalents of ozone. Unless all the phenanthrene has reacted, difficulty is encountered in the crystallization and/or recrystallization of the dialdehyde. 

After passage through the amine solution, any unreacted ozone was absorbed in 2% potassium iodide solution contained in a gas washing bottle. The volume of the ozonated oxygen, passed through the solution and stripped of ozone by the amine solution or potassium iodide solution, was measured with a wet-test meter. The reaction of ozone with tertiary amines was so rapid that at an ozone flow of 56 mg. per minute no excess ozone appeared in the potassium iodide trap during the reaction. The addition of ozone was stopped when the potassium iodide showed the yellow color due to iodine. 

In certain clinical situations, when thyroidal uptake of Tc-pertechnetate should he avoided, pretreatment with an oral dose of potassium perchlorate is used to inhibit uptake. Perchlorate anion shows greater affinity for the transporter than does iodide and is, therefore, a competitive inhibitor of the thyroid iodide trap (Wolff and Maurey 1962). Like pertechnetate, perchlorate is concentrated in the thyroid and is not metabolized. Assuming 100% resorption of an oral dose of 300 mg of KCIO4 and an initial distribution volume of 20 1, the resulting concentration of perchlorate in blood is approximately 10M, sufficient for saturation of the thyroid trapping mechanism (Loberg 1979). 

Iodide transport from the blood into the thyroid acinar cell is accomplished through an energy-requiring, iodide-trapping mechanism that is poorly defined but may involve the Na, K -ATPase coupled to a cotransporter for Na and iodide in the plasma membrane of the acinar cell. 

TSH responsiveness Iodide trapping Thyroglobulin synthesis T4 synthesis T4 to T3 conversion Iodide inhibition of iodide trapping... 

Other interesting information obtained by means of XRF that allows to show the dissociation of hormonogenesis and storage funtion has been reported in the literature. In Hashimoto s thyroiditis a transient iodide trapping defect could be evidenced (3 ) In subacute thyroiditis, iodine stores are depleted (35) and it has been shown that uptake of iodine resumes more rapidely than iodine storage in this disease (Chapter IX) ... 

Barbato A.L., Bekerman C., Refetoff S. 1977 Transient iodide trapping defect in Hashimoto s thyroiditis detected by the combination of radionuclide and fluorescent scanning. Br.J.Radiol. 50 827-830. 

Iodide trapping mechanism is thus adapted in order to maintain the thyroid absolute iodine uptake within the physiological range and to prevent any urinaty iodine loss exceeding the iodine intake. 

It is interesting to notice that the modifications of the iodide trapping mechanism between iodine supplies of 100 to 25 pg/d correspond to an increase of iodide clearance from 30 to 155 ml/mn (ratio 5.0), while corresponding values of U cmly vary from 50 to 87% (ratio 1.7). 

First, I would like to make a short comment on the iodide trapping mechanism in the mammary gland. In studies performed in severe iodine deficiency, in Northern Zaire, it was shown that the iodine concentrations milk in were precisely the same as those found in urine. This constitutes an argument against the concentrating properties of the mammary gland, at least in humans in severe iodine deficiency. Second, my question to Dr. Morreale concerns the debate on the placental transfer of thyroid hormones to the fetus. I wish to... 

The severity of induced irradiation is related to the efficiency of the iodide trapping mechanism in the thyroid gland. Subsequent deleterious effects of thyroidal irradiation are the development of thyroid cancer, thyroid nodules and hypothyroidism (1-2). Radiobiological aspects of the problem have been reviewed by Dr. Malone. The present paper deals with the conditions which are responsable for the irradiation level of the thyroid gland by 1311 jn a given population. 

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