Iodine kinetics

In common with a number of heterocyclic iodinations, kinetic effects are found in the iodination of indole and 2-methylindole [68AC(R)1435], When the substituent effects for the reaction are examined it is clear that any resonance effects from the fused benzene ring are only poorly relayed to the reactive 3-position, and the rates appear to be controlled by inductive effects. A 5-methyl group was more activating than 5-methoxy [69AC(R)799]. 

Eales, J.G., Chang, J.P. and Krank, G. (1982). Effect of temperature on plasma thyroxine and iodine kinetics in rainbow trout. General and Comparative Endocrinology 47,295-307. 

Recent redeterminations of free radical heats of formation by other methods (competitive bromination and iodination kinetic studies) have shown that this technique has, in the past, yielded erroneously low Arrhenius parameters. Several reasons for this have been suggested chain propagation by benzyl radicals. 

Abel (36) has proposed a series of electron transfer reactions involving free radicals similar in principle to those suggested for the iodide-iodine kinetics. He suggests reaction through iodine cations formed for example in the equilibrium ... 

Since 1967 only a small number of studies in India have documented the changes in iodine kinetics in normal subjects without any thyroid disorder. Temporally the changes can be related to the change in iodine intake in... 

Notes Changes in the parameters of iodine kinetics in the National Capital Territory of Delhi with time after salt iodization showed a decrease in thyroid iodine clearance with an increase in urinary and plasma iodine levels. Values are expressed as geometric mean (standard error). 

Table 87.5 Iodine kinetics in Graves disease in the post-iodization era...

Ahluwalia, A., Sood, A., Kumar, R., Khurana, M.L., Pandav, C.S., Karmarkar, M.G. and Padhy, A.K. (2001). Relationship of urinary iodine and iodine kinetic parameters with therapeutic response to carbimazole in Graves, disease. 31st Annual Conference of Endocrine Society of India, Mumbai, India. Ahuja, M.M.S., Gopinath, N. and Bhatia, D. (1974). Indian. Med. Res. 62, 1387-1391. 

Often the amount of administered radioactivity has been used as the criterion to determine whether a patient should be hospitalized or not. T-treated patients, however, do not have the same iodine kinetics. The clearance of from ablated thyroid cancer patients is much faster than from patients treated for hyperthyroidism. The calculations by Coover et al. (2000) enable the nuclear medicine physician to determine the maximum dose to be prescribed to each individual patient. There is a wide... 

Iodine.—Kinetic data on the reactions of iodine atoms with iodide ions and with nitrite ions have been obtained from flash-photolytic studies, and there has been a picosecond study of the dynamics of the cage effect in the recombination of iodine atoms. Iodine has recently been used as a cyanide-ion scavenger to investigate the loss of cyanide from inert transition-metal complexes, and so it is particularly appropriate that the kinetics of the reaction between cyanide and the tri-iodide ion should have been published [equation (29)]. The first term simply represents a... 

A study of the iodination kinetics of dipentene with h in polar and non-polar solvents (EtOH, 1,4-dioxane, CCI4, and PhCl) has revealed that the iodination rate increases with increase in the solvent dielectric constant. The reaction follows a first-, third-, third-, and fourth-order dependence on [I2] in these solvents, respectively. The effect of mixed solvents on iodination rate has also been studied and Arrhenius parameters were calculated. ... 

The rate-determining step in the reaction of Ph3SnCHaCH=CHR, where R = H, Me, or Ph, with iodine is thought to be unimolecular decomposition of a 7r-complex between the organotin compound and the iodine. Kinetic parameters and product distributions have been obtained for this reaction in a variety of solvents, in some cases with the addition of iodide ion to the reaction mixture. In acetone or acetonitrile the mechanism is said to involve attack at the carbon atom y to the tin, but in the more polar solvents methanol and dimethyl sulphoxide there is also some direct electrophilic attack by iodine or iodide ion at the tin. ... 

N.B. The iodination kinetics of o-hydroxy-acetophe-none have been investigated at 25° in aqueous buffer solutions. 

The iodination kinetics of o-hydroxyacetophenone have been investigated at 25° in aqueous buffer solutions. The foregoing analysis assumes that only 1 mol of iodine reacts with each mol of o-hydroxyacetophenone, which may be incorrect. CycUsation probably predominates over the introduction of a second iodine atom into o-hydroxyacetophenone, at least in the early stages of the reaction. There is formation of 3-coumaranone [4569]. 

The reported modifications of iodine kinetics constitute a very effective adaptative mechanism to maintain an adequate secretion of the thyroid hormones in spite of low levels of the iodine supply. 

Dr. Dumont has mentioned that dogs seem never to develop a goiter, in spite of low iodine conditions or administration of antithyroid drugs. Dr. Ermans also mentioned that there are people who adapt better than others to iodine deficiency and hence do not develop goiter. My question therefore is whether this observation both in animals and humans corresponds to different iodine kinetics or to some abnormality at the level of the thyroid follicular cell ... 

Data base on iodine kinetics modelled by Johnsorf ... 

Since logistical issues, to be discussed later, make administration of Kl before or even simultaneously with the radioiodine exposure unlikely, the effectiveness of Kl given following exposure is of considerable importance. Clearly, the earlier the Kl is given, the better, but it is still useful in reducing thyroid dose if administered up to 8 hours and perhaps even 16 hours after a single exposure to fallout, assuming the thyroid has euthyroid iodine kinetics. 

Healthy euthyroid and nongoitrous subjects have been investigated for iodine intake directly and indirectly, by various methodologies including the determination of stable iodine concentration on 24 hr excretion collections (either directly measured on 24 hr urine collections or calculated by the use of the iodine/creatinine or l/Cr ratio), the determination of iodine concentration in the urines, iodine kinetic studies (particularly of the inorganic iodine compartment) and iodine balance studies as well. Most of the values are given as mean standard deviation the standard error of the mean (sem) is specified when used. 

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