Showing papers on "Iodine published in 1982"
TL;DR: The metabolic pathway that allows the synthesis of thyroid hormones from inorganic iodide has been extensively documented at the physiological level, the investigations being greatly facilitated by the use of the iodine isotopes.
Abstract: Publisher Summary This chapter discusses the formation of thyroid hormones. The metabolic pathway that allows the synthesis of thyroid hormones from inorganic iodide has been extensively documented at the physiological level, the investigations being greatly facilitated by the use of the iodine isotopes. However, only the phenomenology of this process can be easily studied in these conditions, not the mechanism. In vivo the situation is complicated by the asymmetry of the thyroid cell (with its apical and basal membranes); by the morphology of the thyroid vesicles and their variability in size and in activity; by large variations in iodide fluxes, which depend not only on changes in dietary intake but also on the regulatory status of the gland; and by the secretion process, which seems to remove preferentially from the colloid either the newly iodinated thyroglobulin or older molecules depending on the physiological situation, etc. In vitro, with the isolated and purified enzyme, these difficulties are eliminated: the system that can be used consists only of a mixture of the enzyme, thyroid peroxidase, H2O2, iodide, and thyroglobulin.
141 citations
TL;DR: Both potassium iodide and dapsone significantly suppressed the generation of oxygen intermediates, except for O2−, and colchicine decreased OH · production.
Abstract: The effects of potassium iodide, colchicine and dapsone on the in vitro generation of polymorphonuclear leukocyte (PMN)-derived oxygen intermediates were investigated. These three drugs have beneficial effects on those conditions in which PMNs play an important pathogenetic role. Three oxygen intermediates, superoxide anion (O2-), hydrogen peroxide (H2O2), hydroxyl radical (OH.) and chemiluminescence were included in assay studies. Dose response studies were performed with therapeutic doses of the drugs (10 microM--mM). We found that both potassium iodide and dapsone significantly suppressed the generation of oxygen intermediates, except for O2-. Colchicine decreased OH. production. Our results show tha these agents to some extent exert their anti-inflammatory effects by interfering with the PMN-dependent production of oxygen intermediates, thus conferring protection from auto-oxidative tissue injury. This may account for their clinical efficacy in many PMN-mediated dermatological diseases.
110 citations
Journal Article•
TL;DR: The findings suggest that iodine is absorbed across the vaginal mucosa and that the subsequent increase in serum total iodine does induce subtle increases in serum TSH concentration, and there was no evidence, however, of overt hypothyroidism in these euthyroid women.
41 citations
TL;DR: In this paper, an iodometric method and a gas-liquid chromatography (g.l.c) method were used to determine the inorganic bromide and total bromine in two soils of widely differing organic matter content, and in eight types of peat.
Abstract: Determinations were made by an iodometric method and by gas-liquid chromatography (g.l.c.) of inorganic bromide and total bromine in two soils of widely differing organic matter content, and in eight types of peat. The volumetric method is responsive to both bromide and iodide and gave a combined value. The g.l.c. method is halogen specific and gave individual values for bromide and iodide. Inorganic bromide represented only a small fraction (1.1% and 8%) of the total bromine in the soils, and was an even smaller fraction (0–1%) in the peats. The highly organic soil contained 141 μg total Br/g dry wt compared with 14 μg/g in the other soil. Total Br in the peats ranged from 11–116 μg/g. The organic soil contained an appreciable amount of total I (46 μg/g), while the total I content of the peats ranged from 3–18 μg/g. The possibility is considered that during the decomposition of peat added to soil, organic Br is released which might act as a potential source of inorganic bromide available to plants, so contributing to bromide residues in edible crops.
32 citations
TL;DR: Benzeneselenenenyl iodide (BEI) is a good reagent for the formation of carbocyclic compounds from diolefins as mentioned in this paper.
Abstract: ‘Benzeneselenenyl iodide’, prepared in situ by the reaction of diphenyl diselenide and iodine, is a good reagent for the formation of carbocyclic compounds from diolefins.
27 citations
TL;DR: In this paper, a method for the determination of between 0 and 5 µg l-1 of total iodine and iodate-iodine present in natural freshwaters is described. But this method is based on the catalytic effect that iodide has on the reaction between ammonium cerium(IV) sulphate and arsenic(III) oxide.
Abstract: Procedures for the determination of between 0 and 5 µg l–1 of total iodine and iodate-iodine present in natural freshwaters are described. Total iodine is determined using the catalytic effect that iodide has on the reaction between ammonium cerium(IV) sulphate and arsenic(III) oxide. An earlier method has been modified rigorously and according to Mark's (1973) recommendations. The analysis of sets of eleven replicate samples showed that the total iodine concentration could be resolved to within ±0.1 µg l–1(±2 × standard error) at the 95% confidence level. The iodate-iodine in the sample is determined by the same procedure after any iodide-iodine has been extracted into chloroform as an ion pair with the tetraphenylarsonium cation. The optimisation of the extraction procedure is described. The analysis of sets of six replicate samples encompassing the 0 to 5.0 µg l–1 range of iodate-iodine concentrations and containing also 1.0 µg l–1 of iodide-iodine returned essentially the same standard errors as for total iodine determination. The effect upon the methods of various substances that could be present in freshwaters is described together with tests conducted upon some organic iodine compounds. The latter experiments suggest that the unsuspected presence of organic iodine compounds in natural waters would be problematic. Analysis for total iodine can be conducted at the rate of approximately 50 samples per hour and that for iodate-iodine at about 20 per hour.
24 citations
23 citations
Journal Article•
TL;DR: A randomised controlled clinical trial of Lugol's iodine against placebo in 44 patients undergoing thyroidectomy failed to show any benefit in terms of reduced bleeding or operative facility after using iodide solution.
Abstract: In a randomised controlled clinical trial of Lugol's iodine against placebo in 44 patients undergoing thyroidectomy we have failed to show any benefit in terms of reduced bleeding or operative facility after using iodide solution.
22 citations
TL;DR: Procedures are given for the analysis of mixtures of ascorbic acid with sulphur-containing amino-acids and cysteine and glutathione, which interfere quantitatively, are masked by cyanoethylation.
22 citations
21 citations
TL;DR: A titrimetric method with amplification has been worked out for the determination of chloramine-T and certain aldoses, based on Leipert determination of iodide produced in the case of chloramines-T by reduction of the determinand with excess of iodides.
TL;DR: In euthyroid subjects with and without goiter and a normalTRH test, the free T4 index (FT4I) increased, and T3 andmaximum TSH after TRH decreased significantly within their normal ranges in relation to increasing iodine intake.
Abstract: This study was located in an area of iodine deficiencyin Western Germany inwhich incidental additional iodineintake occurs predominantly through iodine-containing x-raymedia and drugs. This offered the opportunity to investigate theinfluence of increasing iodine intake on the concentration ofthyroid hormones in 497 euthyroid individuals with and withoutgoiter and in 174 hyperthyroid patients with and without autonomousadenoma. In euthyroid subjects with and without goiter and a normalTRH test, the free T4 index(FT4I) increased, and T3 andmaximum TSH after TRH decreased significantly within theirnormal ranges in relation to increasing iodine intake. The resultssupport the concept of increased TSH secretion as well as theconcomitant alteration of theT3 to T4 ratio in iodine deficiencyand its normalization by increasing iodine intake within a rangeof iodine excretion from 10–1000 eg/g creatinine. In euthyroid individuals with and without goiterand a subnormalTRH test, the FT4I andT3 increased with increasing...
TL;DR: The study shows that a correctly performed per chlorate discharge test will detect minimal inhibition of iodine binding and an important factor is the duration of the follow-up period after perchlorate is given.
Abstract: The kinetics of [123I]iodide uptake were studied when organification of iodine by the thyroid gland was normal and when this binding function was diminished by drugs or disease. Each study was terminated by a sodium perchlorate discharge test (300--600 mg iv) at 60 min or, in some cases, 10--30 min. The results confirmed that binding takes place rapidly in the uninhibited gland with the binding rate constant being at least 0.150 min-1. Discharge from the uninhibited gland is less than 3.5% of the gland uptake when perchlorate is given 60 min after the radioiodide. Subjects with an intrinsic binding defect manifested discharges of 11% of greater of the 60 min uptake and the estimated binding rate constants ranged from 0.003--0.057 min-1. Thyrotoxic subjects receiving 5 mg carbimazole twice daily manifested discharges ranging from 5.4--64.2%, and in those receiving 20 mg twice daily the observed discharges were 67.6--94.6% of the 60 min uptake. The study shows that a correctly performed perchlorate discharge test will detect minimal inhibition of iodine binding. An important factor is the duration of the follow-up period after perchlorate is given. In some of the cases studied discharge was not complete until 60 min after the perchlorate.
TL;DR: The data suggest that the course of subacute thyroiditis might be longer than would appear from the clinical data, the hormonal assays, or the radioactive thyroid uptake data.
Abstract: Evaluation of the thyroid iodine content by x-ray fluorescence was performed in 13 patients throughout the course of subacute thyroiditis. In the initial hyperthyroid phase of the disease, the iodine stores of the thyroid were not completely depleted. The iodine content (6.5 ± 3 mg) was about 2.5 times lower than normal values when thyroiditis had developed in a normal thyroid (10 patients); in 3 patients with goiter, it was elevated (29.6 ± 6.7 mg) but was still within the normal range of euthyroid goitrous patients. After clinical remission, the iodine content of the gland increased only in two patients (+105% and +43% over the initial value, respectively). For the other patients, the iodine content decreased (from −5% to −100% of the initial value). Restoration of iodine stores occurred subsequently and appeared to be a slow and progressive phenomenon; in six patient, the iodine content was still below normal values 12 months after clinical remission (6.6 ± 1.6 mg). These data suggest that the course o...
TL;DR: In this paper, it was shown that the disappearance of molecular iodine is not due to chemical reduction of molecular iodide by organic matter, but rather due to the presence of organic matter in seawater.
TL;DR: In this paper, a simple and rapid method is described for the indirect determination of iodine as an interferent against mercury in cold vapour atomic-absorption spectrophotometry, which is due to the formation of mercury(II) iodide complexes, which in highly acidic solutions cause a decrease in absorbance for mercury (II) proportional to the amount of iodine present.
Abstract: A simple and rapid method is described for the indirect determination of iodine as an interferent against mercury in cold vapour atomic-absorption spectrophotometry. The interference effect is due to the formation of mercury(II) iodide complexes, which in highly acidic solutions cause a decrease in absorbance for mercury(II) proportional to the amount of iodine present. Within certain concentration limits a straight-line calibration graph is obtained, making the determination of small amounts of iodine possible. The detection limit is 2.5 ± 0.7 µg of iodine if it is allowed to interfere (as iodide or iodate) against 100 ng of mercury(II) in 3.0 M nitric acid solution. Interferences for the method are, in general, the same as in the cold vapour atomic-absorption determination of mercury. Chloride and moderate amounts of bromide do not interfere. The possible interference of certain metals, especially the noble metals, is discussed. The proposed method has been used with satisfactory results in the determination of iodine in a seaweed sample (Ascophyllum nodosum) that had been analysed earlier by neutron activation analysis.
Journal Article•
TL;DR: The amount of iodide (I-) that penetrates the skin was determined using an iodide-selective electrode, and it was suggested that about 10% of the applied KI had penetrated the skin.
TL;DR: Incubation of purified carrier proteins for the thyroid hormones in human serum as well as of an extract of rat liver nuclei or of whole nuclei with trace amounts of 125I- or 14C-labeled hormone, followed by irradiation, resulted in covalent binding.
Abstract: Irradiation of the thyroid hormones thyroxine and 3,5,3'-triiodothyronine in the near UV (greater than 300 nm) causes homolytic fission of C--I bonds in both rings. In the presence of hormone-binding proteins, the phenyl radical thus formed, and possibly also the iodine radical, can establish a covalent bond with certain amino acid residues in the binding site. Most if not all of the iodine radicals, however, appear to be reduced to iodide. Incubation of purified carrier proteins for the thyroid hormones in human serum as well as of an extract of rat liver nuclei or of whole nuclei with trace amounts of 125I- or 14C-labeled hormone, followed by irradiation, resulted in covalent binding. This was proven by gel filtration after boiling with guanidine:HCl and by sodium dodecyl sulfate/polyacrylamide gel electrophoresis of the irradiated solutions or of the excluded-peak material obtained after gel filtration. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis of 125I-labeled irradiated nuclear extracts showed a prominent peak (Mr approximately equal to 45,000), sometimes with a shoulder or small peak at Mr approximately equal to 56,000, and a fast-moving peak (Mr approximately equal to 12,000). Similar patterns were obtained with N-bromoacetylthyroxine or N-bromoacetyltriiodothyronine without irradiation. When a suspension of whole nuclei was irradiated instead of nuclear extracts, the shoulder also became a prominent peak.
TL;DR: In glands from animals on a low iodine intake and under chronic TSH hyperstimulation, the integrity of the lysosomes was modified, and the l Lysosomal membrane cohesion was high (increased resistance to freezingthawing and acid autolysis).
Abstract: The role of thyroid lysosomes in hormonal secretion has been studied in rats fed a low iodine diet and receiving chronic increasing iodide supplements. Thyroid secretion was assessed by plasma TSH, T3, and T4 levels and by the concentration and degree of iodination of thyroglobulin (Tgb). Lysosomal activity was evaluated by the total activity of four lysosomal acid hydrolases and by the integrity and fragility of the lysosomal membrane, which were assessed by the latency of acid phosphatase activity and the susceptibility of the particles to physicochemical manipulations. In glands from animals on a low iodine intake and under chronic TSH hyperstimulation, the integrity of the lysosomes was modified (increased free, but sedimentable, acid phosphatase activity), and the lysosomal membrane cohesion was high (increased resistance to freezingthawing and acid autolysis). In animals receiving increasing physiological iodide supplements, plasma TSH levels were normal, and the size of the intrathyroidal iodine po...
TL;DR: The procedure was developed by modification of a pneumoamperometric method which uses the reaction of cyanide with iodine, since the final concentration of iodide is proportional to the initial concentration of cyanides.
Abstract: The procedure was developed by modification of a pneumoamperometric method which uses the reaction of cyanide with iodine, since the final concentration of iodide is proportional to the initial concentration of cyanide. The sample is diluted so that the cyanide concentration is in the range of .5 - 10 ppm, acetate buffer is added to adjust the pH to a value between 4.5 and 6. Excess iodine is added in 95% ethanol, sample is diluted to constant volume and allowed to stand for ca 5 min. Small aliquots of sample are injected slowly into the ion chromatograph through a precolumn containing XAD-4 resin. The excess iodine is adsorbed on this precolumn. The ion chromatograph adsorbs the iodide reaction product on XAD-1 resin. The iodide is removed by elution with sodium phthalate. Retention time is ca 5 min. Contamination of the system may be prevented by the removal of the precolumn for iodine desorption using nitric acid in acetone and water. 2 figures, 3 tables.
TL;DR: Iodine uptake was significantly increased in those animals given BHT into the diet, but the half-life of thyroxine was unchanged or slightly prolonged, and thyroid weight was enhanced at both 500 and 5000 ppm BHT, while liver weight was increased in the latter.
TL;DR: In this paper, the authors investigated the decomposition products from sintered samples by quadrupole mass spectrometry and found that neutral atomic and molecular iodine species desorb from the illuminated surface.
TL;DR: A congenitally goitrous, mentally retarded, hypothyroid child, whose parents were first cousins, was studied for the cause of a strongly positive (86–5%) perchlorate discharge test.
Abstract: SUMMARY
A congenitally goitrous, mentally retarded, hypothyroid child, whose parents were first cousins, was studied for the cause of a strongly positive (86–5%) perchlorate discharge test. The mother had a recidivant goitre after being thyroidectomized in 1971. Her perchlorate discharge test was negative, but she displayed an exaggerated TSH response to TRH administration. The father also showed a negative perchlorate discharge, but he had a large cold nodule in the left thyroid lobe. The father also presented with a retinitis pigmentosa, detected additionally in two of his brothers and three nephews.
Thyroid tissue, obtained from the three patients at surgery, was assayed for thyroid peroxidase (TPO) by three different assays:
1iodination of goitre thyroglobulin;
2oxidation of guaiacol;
3oxidation of iodide.
In a standard iodination assay (100 μM I−) and in a standard guaiacol assay 4–7 mM guaiacol) the TPO activity in the son's tissue was extremely low. Preincubation with haematin did not restore activity. The father displayed a normal TPO activity, but that of the mother was somewhat low. In the iodide oxidation assay employing 12 mM I− in the incubation system, and in iodination and guaiacol assays employing elevated concentrations of substrate, the TPO activity in the son's tissue was quite appreciable and was much closer to that of the parents. Presumably, therefore, the defect in the son's thyroid did not involve an absence of TPO. Rather, the results suggest a qualitative defect in the son's TPO, involving an abnormality in the binding of substrate for oxidation.
Thyroglobulin was isolated from the thyroid soluble fraction by sucrose density gradient centrifugation and its protein and iodine content determined. Thyroglobulin from the son's thyroid tissue contained only 0–043% iodine, compared to 0–45% and 0–29% for mother and father, respectively. The very low iodine content of the son's thyroglobulin accords with the low thyroid peroxidase activity and with the clinical and laboratory findings.
The fact that the parents in the present study are first cousins and that both showed some type of thyroid abnormality suggests that the severely affected son (goitre, mental retardation, and hypothyroidism) is homozygous for a recessive mutant gene.