Radioiodine releases

Marter, W.L. (1963) Radioiodine release incident at the Savannah River Plant. Health Physics, 9,1105-9. 

Yuita K (1979) Transfer of radioiodine from the environment to animals and plants. 1. From soil to plant, in Latest Topics of Radioiodine Released to the Environment, Proc. of 7 NIRS Seminar Research, Chiba, pp. 91-98. Ja. 

Although radioiodine released into the biosphere in North America and Europe reaches people chiefly through cow s milk, the stable iodine content of cow s milk is only about 0.2 ng g (0.004 to 2 /tg g" )(NAS-NRC, 1956). The iodine content of milk varies greatly with... 

However, the dry deposition rate for noble gases, tritium, carbon-14, and nonelemental radioiodine is so slow that this depletion mechanism is negligible within 50 miles of the release point. Elemental o radioiodine and other particulates are readily deposited. This transfer can be quantified as a transfer velocity (where concentration transfer velocity = deposition rate). The transfer velocity is proportional to windspeed and, as a consequence, the rate of depositirm is independent of windspeed since concentration in air is inversely proportional to windspeed. 

NCRP, Protection of the Thyroid Gland in the Event of Releases of Radioiodine, Report 55, National Council on Radiation Protection and Measurements, Bethesda, MD, 1977. 

The ability of KI to block the thyroidal uptake of I and its incorporation into Tg would prove useful in the event of an accident at a nuclear power plant. In such an event, large quantities of radionuclides, including isotopes of radioiodine, could be released into the atmosphere. Administration of KI Thyro-Block) to inhibit the uptake and incorporation of radioiodine would be the most effective means of limiting the potential damage to the thyroid gland. 

Accidents with nuclear reactors or nuclear bombs can expose large numbers of people to several decay products of uranium, and iodine isotopes are among the most abundant compounds released in such reactions. It is therefore logical to use salts of stable isotopes of iodine to prevent the accumulation of radioiodine in a person or population at risk of such exposure. The accidents in Windscale (UK), Three Mile Island (USA), and particularly Chernobyl (Ukraine) drew attention to such problems. The major question is therefore whether the potential adverse effects of stable iodine when given indiscriminately to large... 

Lithium blocks the release of iodine and thyroid hormones from the thyroid and has been used to treat hyperthyroidism, as an adjunct to radioiodine therapy (602-605) and in metastatic thyroid carcinoma (606). However, it can also cause hyperthyroidism. Lithium enhanced the efficacy of radioiodine in 23 patients (607), but was ineffective in a larger comparison of lithium (n = 175) or radioiodine alone (n = 175) (608). In 24 patients with Graves disease, lithium attenuated or prevented increases in thyroid hormone concentration after methimazole withdrawal and radioiodine treatment (602,609). 

Lithium blocks the release of iodine and thyroid hormones from the thyroid and has been used to treat hyperthyroidism, as an adjunct to radioiodine therapy... 

Figure 1 shows the kinetics of release of radioiodinated protein from antibody-complement-treated tumor cells. Guinea pig serum caused the maximum enhanced release compared to untreated cells of I-labeled protein from anti-Forssman antibody-sensitized cells within 10 min of incubation there was no enhanced release of I-labeled protein compared to controls from anti-line-10 antibody-sensitized cells treated with GPC (Fig. lA). Similarly, HuC caused maximal enhanced release of cell surface protein from cells sensitized with either antibody within 10 min (Fig. IE). No enhanced release of membrane protein was observed from cells treated with antibody alone or complement alone (Fig. 1). The values in Fig. 1 represent 23-40% of the total cell-bound activity associated with [ I]ISA.

In hyperthyroidism the beneficial effects of a single dose may be felt in one month, and patients should be reviewed at 6 weeks to monitor for onset of hypothyroidism. The maximal effect of radioiodine may take 3 months. P-adrenoceptor blockade and, in severe cases, an antithyroid drug (but see footnote 1) will be needed to render the patient comfortable whilst waiting this is more likely when radioiodine is used for treatment of patients with relapsing thyrotoxicosis. Very rarely radiation thyroiditis causes excessive release of hormone and thyroid storm. Repeated doses are sometimes needed. 

Radioiodine uptake can be used to test thyroid function, though technetium would be more usual. Scanning may be used for the identification of solitary nodules, and in the differential diagnosis of Graves disease from the less common thyroiditides (e.g. de Quervain s thyroiditis). In the latter, excessive thyroid hormone release caused by follicular cell damage can cause clinical and biochemical features of hyperthyroidism, but uptake is reduced. 

Several papers have reported that radioiodine therapy can lead to worsening of ophthalmopathy, possibly because of the release of thyroid antigens during the inflammatory reaction after I therapy. The worsening can be prevented by glucocorticoid therapy (9). 

A key factor in the apphcation of targeted radiotherapy is the need to maximize the tumour to normal ceU radiation dose ratio. In this study, a new series of peptides — including DOTA-Ahx-Oct (OCT), DOTA-Ahx-Ser-Val-Glu-Phe-Ala-Ahx-Oct (P3) and DOTA-Ahx-Gly-Ser-Val-Glu-Phe-Ahx-Oct (P4), where Ahx is epsilon amino hexyl — developed by Whetstone and Meares of the University of California at Davis, United States of America, were evaluated. These peptides include an additional 5 amino acid sequence, which is cleavable by cathepsin. This modification helps to improve the release and trapping of labelled catabolites within the cell [16.2]. These peptides were directly compared with radioiodinated glycated octreotate (Gluc-TOCA), which was shown to have the best internalization properties of the four peptides studied. A comparison of the binding capacity, internalization, exter-nalization and stability of each peptide was carried out under optimized conditions in order to determine their properties. 

The mechanism by which TRF controls the release of TSH from the pituitary is discussed in Section 2.4. It has been known for several years that the administration of thyroxine (T4) or triiodothyronine (T3) would inhibit the uptake of radioiodine by the thyroids of normal individuals. The administered hormone presumably acted by decreasing the secretion of TSH by the pituitary. This action is the basis of the T3 suppression test described by Werner (Wl). T3 is given to the patient for 7 days. In the normal individual, I uptake by the thyroid will be... 

Radioiodine is also identified as one of the most important fission products that can be released from nuclear facilities, particularly under accident conditions, in terms of its radiological effects on the environment, especially human exposure. A large amount of I delivered to the thyroid almost always leads to hypothyroidism, because of permanent radiation-induced destruction of thyroid cells. The use of potassium iodide (KI) helps in preventing such harmful effects. 

Humans can be exposed to radioiodine, which is released during nuclear accidents, through many pathways. Radioiodine can exist in many forms as water-soluble iodide (H), as contamination in animal milk, as deposits on vegetation, and more likely as airborne in the environment initially released from an accident. It is of interest to note that regardless of any chemical form of radioiodine (either inhaled or consumed through food chain), they all concentrate effectively in the thyroid. 

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