Showing papers on "Iodine published in 1999"
TL;DR: In this article, the authors determined the sink for iodine during oxidation of natural waters, determined the kinetics of several oxidation reactions of HOI, and tested ozone, chlorine, and chloramine as potential oxidants.
Abstract: In aqueous oxidative processes with ozone (O3), chlorine, or chloramine, naturally occurring iodide (I-) can easily be oxidized to hypoiodous acid (HOI) which can react with natural organic matter (NOM) or be further oxidized to iodate (IO3-). Such processes can be of importance for the geochemistry of iodine and for the fate of iodine in industrial processes (drinking water treatment, aquacultures). Whereas IO3- is the desired sink for iodine in drinking waters, iodoorganic compounds (especially iodoform, CHI3) are problematic due to their taste and odor. To assess the sink for iodine during oxidation of natural waters, we determined the kinetics of several oxidation reactions of HOI. Ozone, chlorine, and chloramine have been tested as potential oxidants. Ozone oxidized both HOI and hypoiodite (OI-) (kO3+HOI = 3.6 × 104 M-1 s-1; kO3+OI− = 1.6 × 106 M-1 s-1) in a fast reaction. Chlorine species oxidized HOI by a combination of second- and third-order reactions (k‘ ‘HOCl+HOI = 8.2 M-1 s-1; k‘ ‘‘HOCl+HOI = ...
356 citations
TL;DR: The hypothesis that the escape from the acute Wolff-Chaikoff effect is caused by a decrease in NIS, with a resultant decreased iodide transport into the thyroid is supported, and iodide administration decreases both NIS mRNA and protein expression.
Abstract: In 1948, Wolff and Chaikoff reported that organic binding of iodide in the thyroid was decreased when plasma iodide levels were elevated (acute Wolff-Chaikoff effect), and that adaptation or escape from the acute effect occurred in approximately 2 days, in the presence of continued high plasma iodide concentrations. We later demonstrated that the escape is attributable to a decrease in iodide transport into the thyroid, lowering the intrathyroidal iodine content below a critical inhibitory threshold and allowing organification of iodide to resume. We have now measured the rat thyroid sodium/iodide symporter (NIS) messenger RNA (mRNA) and protein levels, in response to both chronic and acute iodide excess, in an attempt to determine the mechanism responsible for the decreased iodide transport. Rats were given 0.05% NaI in their drinking water for 1 and 6 days in the chronic experiments, and a single 2000-μg dose of NaI ip in the acute experiments. Serum was collected for iodine and hormone measurements, an...
349 citations
TL;DR: No direct correlation is found between selenium tissue content and expression of various thyroidal selenoproteins, indicating that other regulatory factors contribute to or override selenum-dependent expression control, e.g., in thyroid adenoma, carcinoma or autoimmune disease.
166 citations
TL;DR: In this paper, the corrosion and inhibition behaviors of mild steel in aerated sulphuric acid in the presence of propargyl alcohol (PA) and potassium iodide (KI) were investigated using electrochemical methods.
159 citations
TL;DR: The basicity of alkali-metal-exchanged (Na, K, Cs) zeolites X and Y was probed by UV−vis diffuse reflectance spectroscopy of adsorbed iodine as discussed by the authors.
Abstract: The basicity of alkali-metal-exchanged (Na, K, Cs) zeolites X and Y was probed by UV−vis diffuse reflectance spectroscopy of adsorbed iodine. The observed blue shift in the visible absorption spectrum of adsorbed iodine, compared to gaseous iodine, correlated well with the negative charge on the framework oxygen atoms calculated from the Sanderson electronegativity equalization principle. The blue shifts associated with iodine adsorbed on classical catalytic supports like silica, alumina, and magnesia suggest that the iodine adsorption technique for probing basicity is applicable to a wide variety of solids. Iodine was also adsorbed on X and Y zeolites containing occluded cesium oxide formed by decomposition of impregnated cesium acetate. However, the iodine appeared to irreversibly react on these strongly basic samples, possibly forming an adsorbed triiodide ion. As a complement to the adsorption studies, the activity of alkali-metal-containing zeolites for the base-catalyzed formation of ethylene carbon...
128 citations
TL;DR: The data suggest that various agents known to affect iodide transport are capable of differentially altering NIS gene expression and function in cultured thyroid cells.
Abstract: The sodium iodide symporter (NIS), first identified in FRTL-5 cells, plays a critical role in iodide transport in the thyroid gland and in the production of the iodine-containing thyroid hormones. The aim of our study was to examine the regulation of NIS RNA steady-state levels and protein expression as well as functional activity in FRTL-5 cells. FRTL-5 cells cycling in media containing thyrotropin (TSH) were incubated for 48 hours with dexamethasone (10-8-10-5 M), triiodothyronine (T3; 10-9-10-6 M), methimazole (100 μM), propylthiouracil (PTU; 100 μM), perchlorate (10 μM) and potassium iodide (40 μM). In other experiments, cells were treated for 48 hours with various cytokines including interleukin-6 (IL-6) (100 U/mL), interferon-γ (IFN-γ) (100 U/mL), tumor necrosis factor-α (TNF-α) (10 ng/ml), IL-1α (100 U/mL), and IL-1β (100 U/mL). Northern blot analysis using a 32P-labeled rat NlS-specific cDNA probe (nucleotides 1397-1937) revealed NIS mRNA as a single species of approximately 3 kb. When normalized ...
112 citations
TL;DR: Iodine in tap water was a major determinant of regional differences in iodine intake in Denmark and for the iodine content of infant formulas.
Abstract: The iodine intake level of the population is of major importance for the occurrence of thyroid disorders in an area. The aim of the present study was to evaluate the importance of drinking water iodine content for the known regional differences in iodine intake in Denmark and for the iodine content of infant formulas. Iodine in tap water obtained from 55 different locations in Denmark varied from <1.0 to 139 microg/l. In general the iodine content was low in Jutland (median 4.1 microg/l) with higher values on Sealand (23 microg/l) and other islands. Preparation of coffee or tea did not reduce the iodine content of tap water with a high initial iodine concentration. A statistically significant correlation was found between tap water iodine content today and the urinary iodine excretion measured in 41 towns in 1967 (r=0.68, P<0.001). The correlation corresponded to a basic urinary iodine excretion in Denmark of 43 microg/24h excluding iodine in water and a daily water intake of 1.7 l. The iodine content of infant formulas prepared by addition of demineralized water varied from 37 to 138 microg/l (median 57 microg/l, n=18). Hence the final iodine content would depend heavily on the source of water used for preparation. We found that iodine in tap water was a major determinant of regional differences in iodine intake in Denmark. Changes in water supply and possibly water purification methods may influence the population iodine intake level and the occurrence of thyroid disorders.
101 citations
TL;DR: In this article, a method allowing the determination of iodine species in milk and infant formulas was developed based on the coupling of size-exclusion chromatography (SEC) with on-line selective detection of iodide by ICP MS.
Abstract: A method allowing the determination of iodine species in milk and
infant formulas was developed. It was based on the coupling of
size-exclusion chromatography (SEC) with on-line selective detection of
iodine by ICP MS. Iodine species were quantitatively eluted with 30 mM
Tris buffer within 40 min and detected by ICP MS with a detection limit
of 1 µg l–1 (as I). A systematic study of
iodine speciation in milk samples of different animals (cow, goat) and humans,
of different geographic origin (several European countries) and in infant
formulas from different manufacturers was carried out. Whey obtained after
centrifugation of fresh milk or reconstituted milk powders contained more than
95% of the iodine initially present in milk in all the samples
investigated with the exception of the infant formulas in which only
15–50% of the total iodine was found in the milk whey. An addition
of sodium dodecyl sulfonate (SDS) improved considerably the recovery of iodine
from these samples into the milk whey. Iodine was found to be principally
present as iodide in all the samples except infant formulas. In the latter, more
than half of the iodine was bound to a high molecular (>1000 kDa)
species. The sum of all the species recovered from a size-exclusion column
accounted for more than 95% of the iodine present in a milk sample. For
the determination of total iodine in milk a rapid method based on
microwave-assisted digestion of milk with ammonia followed by ICP MS was
optimized and validated using CRM 151 Skim Milk Powder.
96 citations
TL;DR: In this paper, a mesoporous silica material containing self-assembled mercaptan groups was used for separation of Hg(II) from potassium iodide/sulfate wastes.
Abstract: Separation of Hg(II) from potassium iodide/sulfate wastes was studied using a novel mesoporous silica material containing self-assembled mercaptan groups. The adsorbent, consisting of self-assembled mercaptan on mesoporous silica (SAMMS) developed at Pacific Northwest National Laboratory (PNNL), was characterized as to its specificity, adsorption capacity, and kinetics for separation of mercury from potassium iodide/sulfate solutions. Aqueous speciation calculations indicated that a major fraction (92–99%) of dissolved mercury in the potassium iodide/sulfate wastes solutions existed as HgI2− 4species. The adsorption data showed that the mercury adsorption capacity of SAMMS material increased with decreasing iodide concentrations. The magnitude of calculated free energy of adsorption indicated that mercury adsorption on this adsorbent is typical of soft acid–soft base interactions. High specificity for anionic complexes of Hg(II) by the SAMMS material was confirmed by distribution coefficient measurements....
93 citations
TL;DR: General qualities of aqueous iodine solutions are deduced, such as reactivity, stability, and analytical aspects, and major disinfection‐orientated properties such as microbicidal activity, irritation, and incorporation effects are estimated.
Abstract: Although they have been in use for nearly 170 years, the mode of action of iodine-based disinfectants is not yet clearly understood, as is manifested, for example, in diverging judgements about the relevance of the individual iodine species. Although studies based on calculated equilibrium concentrations in pure iodine solutions have already been done, there is a lack of knowledge about iodine solutions in the presence of additional iodide which would be of intrinsic importance for disinfection practice. Therefore, a re-calculation was undertaken considering variations of this parameter in the pH range 0-14. The presented calculations concern fresh iodine solutions not affected by disproportionation (iodate formation) and provide information about the equilibrium concentrations of the species I, I2, I3, I5-, I6(2-), HOI, O1-, HI2O-, IO2- and H2OI+. Additional iodide and the pH value have a very pronounced influence on the individual equilibrium concentrations (several powers of ten); hence, conditions can be indicated where the number of species of virtual importance is drastically reduced. In the most common case with iodine in the presence of additional iodide at pH 10. The stability problem (i.e. rate of iodate formation) arising at pH > 6 can be reduced to hypoiodous acid, as manifested in the simple rate law d[IO3]/dt = 0.25 [HOI]3/[H+] which allows an estimation of stability under weakly alkaline conditions. The results of this study allow us to deduce general qualities of aqueous iodine solutions, such as reactivity, stability, and analytical aspects, and to estimate major disinfection-orientated properties such as microbicidal activity, irritation, and incorporation effects. Though the calculations consider primarily preparations devoid of polymeric organic compounds capable of complexing iodine species, the results can be largely transferred to iodophoric preparations.
88 citations
TL;DR: In this article, it was shown that illumination of the chlorine dioxide−iodine−malonic acid reaction with visible light suppresses oscillations and shifts the steady state of the reaction to lower concentrations of iodide ions.
Abstract: We show that illumination of the chlorine dioxide−iodine−malonic acid reaction with visible light suppresses oscillations and shifts the steady state of the reaction to lower concentrations of iodide ions. In the system with starch, illumination results in a strong decrease of the steady-state concentration of the triiodide−starch complex. We suggest a simple mechanism, in which iodine atoms produced by photodissociation of molecular iodine initiate reduction of chlorine dioxide to chlorite and oxidation of iodide ions to iodine. This results in a decreased amplitude of oscillations and, at more intense illumination, the cessation of oscillations. Illumination also lowers the steady-state concentrations of iodide and the triiodide−starch complex. Results obtained from numerical simulations are in good agreement with the experimental data.
TL;DR: A method for the determination of iodide, iodate, organic iodine, and total iodine in seawater was developed in this paper, where the behaviors of loading, washing, and eluting of iodides, iodates, and organic iodates were described.
Abstract: A method for the determination of iodide, iodate, organic iodine, and total iodine in seawater was developed. The behaviors of loading, washing, and eluting of iodide, iodate, and organic iodine in...
TL;DR: In this paper, the roles of microbial activities in the accumulation of iodine in soils and its loss from soils were studied, and concentrations of stable iodine in several type of soils were determined by inductively coupled plasma-mass spectroscopy.
Abstract: The roles of microbial activities in the accumulation of iodine in soils and its loss from soils were studied. Concentrations of stable iodine in several type of soils were determined by inductively coupled plasma-mass spectroscopy. High iodine concentrations were found in upland soils, particularly in Andosol, whereas the concentrations in lowland soils were considerably lower. Accumulation of iodine in soils was explained by the effects of microorganisms or their products (e.g., enzymes), or both. Iodine was observed to be desorbed from the flooded soils because of the reducing conditions (low Eh) created by the microbial activities. Evaporation of biogenerated methyl iodide from the soilplant system, specifically from rice plants, may also decrease the iodine concentrations in lowland soils.
TL;DR: The incidence of isolated hypothyroxinemia or biochemical hypothyroidism doubled between midgestation and term in group A, suggesting that moderate iodine deficiency may result in maternal thyroid failure during the later stages of pregnancy.
Abstract: In an effort to assess the impact of moderate iodine deficiency on maternal thyroid function during pregnancy, we measured serum thyrotropin, total and free thyroid hormones, thyroid-binding globul...
TL;DR: A hyphenation of capillary electrophoresis to inductively coupled plasma mass spectrometry (ICP‐MS) was employed for the speciation of iodine in human serum and urine and found that spiked T4 or T3 immediately bound to TBG.
Abstract: A hyphenation of capillary electrophoresis (CE) to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the speciation of iodine. The separation method used a buffer sandwich of phosphate (pH 2.3), NaOH, sodium dodecyl sulfate (SDS) and borate buffer (pH 8.3) for stacking, aiming at sufficient separation of iodide, iodate, thyroxine (T4) and triiodothyronine (T3). These four iodine species were separated within 15 min and subsequently detected during a pressure-driven detection step (baseline-separated) at 19.5, 29.1, 36.6 and 42.2 s. The detection limits were determined at 0.08 microg I/L (iodide), 0.3 microg I/L (iodate), 3.5 microg I/L (thyroxine) and 2.5 microg I/L (triiodothyronine). This method was applied on iodine speciation in human serum ("healthy" and after thyroid gland operation) and urine. The serum from the healthy person contained iodide (13 microg I/L), T4 (61 microg I/L) and T3 (7.5 microg I/L), whereas the serum from the thyroid-operated person lacked T3. As no "free" I-hormones are known in serum, the role of the thyroid hormone binding globulin (TBG) was investigated. We found that spiked T4 or T3 immediately bound to TBG. Investigations on human urine showed only a peak for iodide.
TL;DR: While the precise mechanisms by which mutant NISs cause iodide trapping defect are still unknown, preliminary data suggest that 354P interferes with the iodide transport function rather than targeting to the cell membrane.
TL;DR: The level of dietary iodine intake and the iodine content of breast milk of Korean lactating mothers is found to be much higher than in other countries and there was a significant reduction in the levels of iodine in human milk depending on the lactation period.
Abstract: Korea's food culture includes the consumption of seaweed, which is abundant and has a high iodine content. Because it is customary to serve seaweed soup to new mothers, the consumption of seaweed increases dramatically when a woman is lactating. The present study was undertaken for the purpose of determining the iodine content in human milk of Korean lactating mothers according to dietary iodine intake. The iodine content of human milk and dietary iodine intake from 50 lactating mothers were analyzed at 2 to 5 days and at 4 weeks postpartum. The dietary iodine intake was assessed by the 24-hour recall method. The iodine content in human milk was analyzed by neutron activation analysis (NAA). The average daily iodine intake of lactating mothers was 2744 micrograms at 2 to 5 days postpartum, decreasing significantly to 1295 micrograms at 4 weeks postpartum. The major sources of iodine were seaweed (87%) and cows' milk (7%). The average iodine content in colostrum and mature milk was 2170 micrograms/l and 892 micrograms/l, respectively. There was a significant reduction in the levels of iodine in human milk depending on the lactation period. A significant correlation between maternal iodine intake and iodine content of human milk was observed (P < 0.0001). The frequency of seaweed soup intake in lactating mothers seems to be a modifying factor in the iodine intake level and the iodine content in human milk. The level of dietary iodine intake and the iodine content of breast milk of Korean lactating mothers is found to be much higher than in other countries.
TL;DR: It is now possible to use gene diagnostics of this unique NIS mutation to identify patients with congenital hypothyroidism due to an iodide transport defect in this family and to determine the carrier state of potential parents for genetic counseling and arranging rapid and early diagnosis of their infants.
Abstract: We previously reported nine children with an autosomally recessive form of congenital hypothyroidism due to an iodide transport defect in a large Hutterite family with extensive consanguinity living in central Canada. Since the original report, we have diagnosed congenital hypothyroidism by newborn TSH screening in 9 additional children from the family. We performed direct sequencing of the PCR products of each NIS (sodium/iodide symporter) gene exon with flanking introns amplified from genomic DNA extracted from peripheral blood cells of the patients. We identified a novel NIS gene mutation, G395R (Gly395-->Arg; GGA-->AGA), in 10 patients examined in the present study. All of the parents tested were heterozygous for the mutation, suggesting that the patients were homozygous. The mutation was located in the 10th transmembrane helix. Expression experiments by transfection of the mutant NIS complimentary DNA into COS-7 cells showed no perchlorate-sensitive iodide uptake, confirming that the mutation is the direct cause of the iodide transport defect in these patients. A patient who showed an intermediate saliva/serum technetium ratio (14.0; normal, > or = 20) and was considered to have a partial or less severe defect in the previous report (IX-24) did not have a NIS gene mutation. It is now possible to use gene diagnostics of this unique NIS mutation to identify patients with congenital hypothyroidism due to an iodide transport defect in this family and to determine the carrier state of potential parents for genetic counseling and arranging rapid and early diagnosis of their infants.
TL;DR: In this article, a method for quantitative speciation of iodide in soil was proposed, in which iodide extracted from soil samples with tetrametBPyIammonium hydroxide (TMAH) was separated into humic and fnalvic acid fractions at pH4 1.5 after the addition of ascorbic acid into the TMAH extract to reduce iodate into iodide.
Abstract: In order to analyze the behavior and phytoxicity of iodine in soil, the chemical forms of soil iodine must be identified. Therefore, a method for quantitative speciation of iodine in soil was proposed. Iodine extracted from soil samples with tetrametBPyIammonium hydroxide (TMAH) was separated into humic and fnalvic acid fractions at pH4 1.5 after the addition of ascorbic acid into the TMAH extract to reduce iodate into iodide. Since the iodide in the TMAH extract was recovered in the fdvic acid fraction by this procedure, iodine contained in the haamic acid fraction was considered to be organically bound. Podine in the fulvic acid fraction was separated into organic iodine bound to fnlvic acids and the total inorganic iodine. Furthermore, iodine soluble from soil in 0.1 mol L-1 potassium chloride was assumed to correspond to the amount of total iodide in soil, and from the difference in the concentration of total inorganic iodine and soluble iodide, the amount of iodate was calculated. By the app...
TL;DR: The data suggest that KA interrupts thyroid function, primarily by inhibiting iodine intake, consequently causing a decrease in serum T(3) and T(4).
Abstract: To clarify the mechanism of tumorigenesis by kojic acid (KA), dose and time dependence of iodine uptake in the thyroid gland and serum thyroid stimulating hormone (TSH) and thyroid hormone levels were investigated in F344 rats fed a diet containing 2% KA. After 4 weeks, thyroid hyperplasia was apparent in males, associated with a decrease in (125)I uptake into the thyroid gland to only 3% of that in controls. The serum triiodothyronine (T(3)) and thyroxine (T(4)) levels dropped to 0.36 ng/ml, 1.7 micrograms/dl from the initial values of 0.61 ng/ml, 4.0 micrograms/dl and TSH increased seven times to 15 ng/ml. In females, the effects on thyroid weight and (125)I uptake were less prominent, although the changes in serum T(3), T(4) and TSH levels were similar to those in males. Time-dependent changes in serum T(3), T(4) and TSH levels correlated with the inhibition of iodine uptake in the thyroid. Inhibition of organic iodine formation was only observed after 3 weeks treatment. On return to the control diet, normal serum T(3), T(4) and TSH levels became evident within 48 h in both sexes. These data suggest that KA interrupts thyroid function, primarily by inhibiting iodine intake, consequently causing a decrease in serum T(3) and T(4). Increased TSH from the pituitary gland in turn stimulates thyroid hyperplasia, which is reversible on withdrawal of KA.
TL;DR: In this article, surface and bottom water samples were collected along the Nile River estuary for the voltammetric determination of dissolved iodine species during high and low-flood periods.
TL;DR: In this population of school children with initially a low to moderate level of iodine deficiency, the group receiving salt with 25 ppm (group A) was not iodine deficient on all indicators after 18 months of study.
Abstract: Objective: The purpose of this trial was to compare three different iodine interventions. Design: School children aged 8‐10 years were randomized into one of three groups: group A was provided with iodized salt by researchers with an iodine concentration of 25 ppm; group B purchased iodized salt from the market; and group C was similar to group B with the exception that they were given iodized oil capsules containing 400 mg iodine at the beginning of the study. Salt iodine content was measured bimonthly for 18 months and indicators of iodine deficiency were measured at baseline and 6, 9, 12 and 18 months after randomization. Results: The prevalence of abnormal thyroid volumes, based on the World Health Organization (WHO) body surface area reference > 97th percentile, was 18% at baseline and declined to less than 5% by 12 months in groups A and C, and to 9% after 18 months in group B. Results for goitre by palpation were similar. The median urinary iodine was 94 m gl -1 at baseline and increased in all groups to > 200 m gl -1 at the 6-month follow-up. Conclusions: In this population of school children with initially a low to moderate level of iodine deficiency, the group receiving salt with 25 ppm (group A) was not iodine deficient on all indicators after 18 months of study. When the iodine content of the salt varied, such as in group B, by 18 months thyroid sizes had not yet achieved normal status.
Journal Article•
TL;DR: The retention of iodine varied with the kind of foods and also was influenced by the water content of cooked food, and the loss was greater in fortified salt stored at 37 degrees C and under 76% humidity than in that at 20-25 degreesC and under lower humidity.
TL;DR: In this article, a modified carbon paste electrode was constructed by incorporating Cu(Qui)(NO 3 ) 2 into a carbon-paste composed of graphite powder and Nujol, which resulted in a deposit of iodide ions on the electrode surface through a ligand exchange reaction.
TL;DR: In this article, atmospheric measurements of methyl iodide and dimethyl sulphide were carried out at Mace Head, western Ireland, over a 4-week period in July 1996, showing a clear association, indeed statistical analysis indicated a very significant degree of covariance.
TL;DR: In this review, recent progress in the understanding of transepithelial iodide transport in the thyroid is summarized.
Abstract: Thyroid hormone is an essential regulator of developmental growth and metabolism in vertebrates. Iodine is a necessary constituent of thyroid hormone. Due to the scarcity and uneven distribution of iodine on the Earth's crust, the structure of the thyroid gland is adjusted to collect and store this element in order to secure a continuous supply of thyroid hormone throughout life. Still, disease resulting from hypothyroidism due to iodine deficiency is a global health problem, illustrating the great biological significance that iodine saving mechanisms have evolved. Iodide is accumulated together with prohormone (thyroglobulin) in the lumen of the thyroid follicles. The rate-limiting step of this transport is the sodium/iodide symporter located in the basolateral plasma membrane of the thyroid follicular cells. Iodide is also transferred across the apical plasma membrane into the lumen where hormonogenesis takes place. In this review, recent progress in the understanding of transepithelial iodide transport in the thyroid is summarized.
TL;DR: The results indicated that there was a difference between the effects of AMD versus those of physiological doses of iodide, indicating a possible persistence of the Wolff-Chaikoff effect due to a constant high intracellular iodide level.
Abstract: Amiodarone (AMD) is a powerful anti-arrhythmic drug used for the treatment of a wide variety of cardiac arrhythmias and its most striking feature is its high iodine content. Thyroid dysfunction is a limiting side-effect of the drug and both AMD-induced hypothyroidism (AIH) and AMD-induced thyrotoxicosis (AIT) are reported. To examine the hypothesis that altered bioavailability of iodine is a contributing event in the pathogenesis of AIH, we compared the effects of AMD and inorganic iodine in vitro on events involved in the process of thyroid autoregulation. FRTL-5 cells and JP26 CHO cells (transfected with the human TSH receptor) were exposed to AMD or NaI in the presence of TSH, and cAMP production was measured as an indicator of cellular function. Forskolin and cholera toxin were also used to determine the possible target sites of AMD and iodide. Our results indicated that there was a difference between the effects of AMD versus those of physiological doses of iodide. The inhibitory effects of AMD occurred at lower concentrations of iodide than those seen in the NaI-treated cells. The effects of AMD were irreversible indicating a possible persistence of the Wolff-Chaikoff effect due to a constant high intracellular iodide level. The inhibitory effects of AMD (also seen at supraphysiological doses of iodide) were partially overcome by forskolin but not by cholera toxin indicating an effect on TSH receptor interactions with the other signal transduction elements such as G proteins and adenylate cyclase. The persistence of the Wolff-Chaikoff effect through loss of autoregulation may be a mechanism of the observed hypothyroidism in some patients taking AMD. The combined effects of the constant release of iodide together with the drug toxicity may be the mechanism for the observed effects.
TL;DR: In this article, the status of oil and fat samples is judged by their peroxide value (PV), an index that seeks to determine the peroxide content by measuring how much iodine is liberated by the sample from iodide in an acidic medium in a specified time period.
Abstract: The status of oxidation of oil and fat samples is normally judged by their peroxide value (PV), an index that seeks to determine the peroxide content by measuring how much iodine is liberated by the sample from iodide in an acidic medium in a specified time period. At peroxide levels of interest, not only does this approach require considerable analyst skill, the method is inherently flawed because of the considerable differences in the rates at which different peroxides liberate iodine from iodide and potentially also the consumption of nascent iodine by unsaturated sites. We propose here a substantially less biased method based on the oxidation of Fe(II) to Fe(III) by peroxides, followed by the colorimetric detection of the latter as the thiocyanate complex. The system is automated through flow injection photometry. A methanol−butanol mixed solvent is used as the carrier stream. Samples, generally prediluted in the same solvent, are injected into this carrier; streams bearing Fe2+ and SCN- are separatel...
TL;DR: In this article, reactions of iodine and phenol were investigated to determine which iodophenols were produced and their odor properties and their reactions were fast and nearly complete within 1 hour.