Showing papers on "Iodine published in 1984"

Synthesis of monodisperse living poly(vinyl ethers) and block copolymers by the hydrogen iodide/iodine initiating system

Abstract: Polymerisation d'alkyl vinyl ethers (CH 2 =CH−OR; R=CH 3 , C 2 H 5 , i-C 3 H 7 , n-C 4 H 9 et n-C 18 H 33 )

Breast milk iodide: reassessment in the 1980s.

Abstract: In addition to iodized salt, the American diet is inadvertently supplemented with iodine from other foods, such as bread and cow's milk. The iodine content of breast milk has not been assessed recently in this country. Sixty-one samples of breast milk from 37 women were analyzed for iodide content using an iodide-selective electrode method. Mean breast milk iodide level on initial samples for this population was 178 micrograms/L (range 29 to 490 micrograms/L), about four times the recommended daily allowance for infants. Iodide levels in breast milk did not correlate with the age of the infant (ie, stage of lactation). There was a significant correlation between the iodide level in the breast milk and dietary iodine as estimated by a food frequency questionnaire, and iodized salt intake was significantly related to the iodide content of the breast milk.

Pseudo-catalytic degradation of hydrogen peroxide in the lactoperoxidase/H2O2/iodide system.

Abstract: Non-stoichiometric (excessive) consumption of hydrogen peroxide (H2O2), which was observed in various lactoperoxidase-catalysed reactions, was tested in the lactoperoxidase/H2O2/iodide system. In preliminary experiments the suitability of the system was tested with special regard to the triiodide (I−3) absorption and the I2/I−3 equilibrium. Triiodide equilibrium concentrations evaluated theoretically and experimentally were compared after adding a known amount of iodine (I2) to solutions containing variable I− concentrations. A close fit of the two methods was only obtained if experiments were carried out in pure aqueous or 0.001 M H2SO4 medium. The presence of various anions, e.g. OH− and Cl−, led to a measurable decrease in I−3 and I2 equilibrium concentrations. These ions are able to displace competitively I− in forming association products with I+ and I2. When I+ and I2 were generated enzymatically by lactoperoxidase and hydrogen peroxide, additional interactions with H2O2 were observed. Depending on the enzyme and iodide concentrations, variable amounts of H2O2 disappeared non-productively. Due to its ambivalent redox reactivity, part of the H2O2 is not reduced to H2O in the enzyme-catalysed generation of iodine, but undergoes oxidation to O2 by an oxidized iodine compound. This suggests a pseudocatalatic side reaction which can competitively interfere with the I2 I−3 generation or (and) the iodination reaction.

Iodine leach for the dissolution of gold

Abstract: A process for the hydrometallurgical recovery of gold from materials containing gold comprising leaching the materials with a lixiviant containing iodine. To a solution concentrated with natural salts is added elemental iodine until saturated, whereupon mineral sulfides in the ore zone charged with this solution react with the iodine to form iodide. Additional elemental iodine is then added to this iodide-bearing solution until the desired concentration of total iodine and ratio of iodine to iodide are achieved for optimum leaching. The lixiviant is then circulated through the ore zone until all the gold is dissolved. Gold is subsequently recovered on activated charcoal. The excess iodide formed during the process is reoxidized to iodine electrochemically in a special diaphragm cell to regenerate the lixiviant.

Prolonged Iodine Clearance with a Depletion Regimen for Thyroid Carcinoma: Concise Communication

Abstract: Prior studies suggested iodine depletion as a means of enhancing radioiodine uptake into metastases from well-differentiated thyroid cancer. Accordingly the authors have measured inorganic iodine clearance, total body iodine, tumor and total-body retention of radioactive iodine before and during a diet-and-diuretic regimen designed to induce iodine depletion. Total-body iodine decreased by 25% to 66%. The amount of radioiodine taken up and retained by tumor tissue increased 146% following the depletion regimen in three studies (two patients). However, because the iodine clearance decreased by 56%, the total-body radiation per standard 150-mCi dose increased by 86%. Consequently, the increase in lesion irradiation relative to the increment delivered to the total body was only 46%. They conclude that iodine-depletion regimens are less effective than prior studies suggest.

Autoregulation by Iodine of Thyroid Protein Synthesis: Influence of Iodine on Amino Acid Transport in Cultured Thyroid Cells*

Abstract: Studies were conducted to determine whether the inhibitory effect of iodine on thyroid protein synthesis could be explained by a reduction in intracellular amino acid transport. The nonmetabolizable amino acid [14C]cycloleucine was used as a probe for the L system of neutral amino acid transport in dog thyroid cells during the initial 24 h of primary culture. Uptake of cycloleucine was linear for up to 30 min. At all time points, cycloleucine transport was reduced in cells preincubated for 3 h in Nal (10−4 m). Inhibition (in a typical experiment) by Nal of cycloleucine transport (10 min) was 19%, 42%, and 69% at 10−6, 10−5, and 10−4 m iodide, respectively. Methimazole (3 IDM) together with iodide abolished the inhibitory effect of iodide on cycloleucine transport, implying the necessity of iodide organification. Methimazole itself did not significantly alter cycloleucine transport. T3, T4, MIT, and DIT similarly did not inhibit cycloleucine transport. Nal did not inhibit cycloleucine transport in cells la...

Iodinated compounds and thyroxine binding to albumin in human breast milk.

Abstract: Summary: Mature human milk samples from young healthy women on an equilibrated diet contained a mean of 81 ng/ml total iodine. Iodide represented a mean of 77% of the total iodine. Of the 22 ng/ml organic iodine, there was about 1 ng thyroxine and triiodothyronine and, after pepsin hydrolysis, up to 40% of organic iodine in monoiodotyrosine form. By electrophoresis, after incubation with radioactive thyroid hormone, we found an absence of binding on thyroxine-binding globulin, but thyroxine and triiodothyronine were bound to albumin with a maximal capacity 50 times higher than in human serum. All these differences did not favor transport of iodinated compounds from maternal serum to milk. In conclusion, milk iodide was taken up by newborn thyroid to make thyroid hormones.

Process for separating iodine and its compounds from the carbonylation products obtained by subjecting dimethylether, methyl acetate or methanol to a carbonylation reaction

Abstract: The disclosure relates to a process for separating iodine and its compounds from the carbonlyation products acetic acid, acetic anhydride or ethylidene diacetate obtained by subjecting dimethylether, methyl acetate or methanol to a carbonylation reaction For reducing the quantity of total iodine contaminating the carbonlyation products to less than 20 ppb iodine, the disclosure provides for the carbonylation products to be treated at temperatures of 20° to 250° C with an alkyl or aryl phosphine or a heterocyclic aromatic nitrogen compound and at least one of the metals copper, silver, zinc or cadmium or their compounds and to be distillatively separated from the iodine thereby fixed in non-volatile form

Molecules of CH3I and n-C3F7I as iodine atom donors in a pulsed chemical oxygen-iodine laser

Abstract: The laser output energies obtained as a result of photolysis of RI-O2(1Δg)-O2(X3Σg-)-Ar mixtures were determined in a comparison of CH3I and n-C3F7I as donors of atomic iodine in a pulsed chemical oxygen-iodine laser.

Iodine toxicosis in six herds of dairy cattle.

Abstract: Daily iodine intake estimated to range from greater than 68 to 600 mg/animal/day was associated with signs referable to iodine intoxication in adult cows in 6 herds of dairy cattle. Signs were reversed by lowering supplemental intake to less than 12 mg/animal/day. Results of biochemical tests other than those for serum and milk iodine were not diagnostic. Serum iodine concentrations were 2.6 to 6.9 times the mean iodine concentration found in 12 control cows, each receiving 12 mg of iodine/day. Milk iodine concentrations were 3.6 to 13.6 times milk iodine concentrations in the control cows.

Iodine intake in an urban environment: a study of urine iodide excretion in Auckland.

Abstract: Dietary iodine intake was estimated by measurement of iodide in random overnight 12 hr and 24 hr urine samples. Urinary iodide excretion was measured in 231 healthy females comprising 127 female secondary students (ages 16-19), 27 female tertiary students (17-23 yr), 42 female laundry workers (18-52 yr) and 26 pregnant women in the third trimester (18-40 yr). Urine iodide excretion was also examined in a group of 28 patients attending a thyroid clinic, with thyroid disease of diverse aetiology and in 34 patients taking the antiarrhythmic drug amiodarone for control of cardiac arrhythmias. The mean daily urine iodide excretion was 2.4 mumol/day (0.9-5.8 mumol/day) and iodide to creatinine ratio 0.21 mumol/mmol (0.09-0.29). Iodine deficiency (less than 0.4 mumol/day) was not observed in any subject. Excessive iodine (greater than 8 mumol/day) was found only in patients known to be taking iodine-containing drugs and in one normal individual. The urine iodide was normal in 154 female students, 14 of whom had a trivial thyroid enlargement. The study suggests that dietary sources other than iodised salt contribute significantly to dietary iodine intake and that residual goitre in the community is not secondary to deficiency or excess of dietary iodine.

Transient thyrotoxicosis in endemic goitre patients following exposure to a normal iodine intake.

Abstract: SUMMARY Twenty-three endemic goitrous subjects (goitre grade: III and IV) that were living in a chronic iodine-deficient area (iodine intake: less than 40 μg I/d) were submitted to clinical and laboratory evaluation within 3–8 weeks of arrival at the metropolitan area of Sao Paulo, where daily iodine intake is estimated to be 150–200 μg I/d. Eight patients developed a mild thyrotoxic state (T4 = 14.7 ± 2.3 μg/dl, T3 = 279 ± 55 ng/dl, no TSH response to TRH). Five additional subjects, although euthyroid, had a blunted TSH-response to TRH, and the remaining ten patients were euthyroid and had a normal TSH response to TRH. Thyrotoxicosis was associated with larger goitres (mean thyroid weight: 133 ± 46 g), with high thyroid uptake of RAI (mean 24 h 131 I uptake: 40 ± 15%) but not with increased urinary iodine excretion. Serum Tg levels were more elevated in the first two groups of patients (respectively, geometric means 68 and 72 ng/ml), than in the euthyroid, TRH-responsive group (52 ng/ml). Thyrotoxicosis resolved spontaneously after three to six months without the need for any specific medication. It was concluded that a relatively small and normal iodide intake due to regular consumption of iodized salt and industrialized foods may induce a transient form of thyrotoxicosis in endemic goitre patients arriving into urban areas.

Iodide excretion in a salt-restriction trial.

Abstract: Twenty-four hour urinary iodide excretion was measured twice, with a four month interval, in 133 individuals who were in a 12-month salt-restriction study in an area where iodine-deficiency goitre was once common and where most household salt is iodised. Half the subjects were salt restricted; their mean 24 h sodium excretion after eight months was 89 mmol for men and 73 mmol for women. Iodide excretion correlated with sodium excretion in the whole group on each occasion. After eight months mean 24 h iodide excretion in the salt-restricted group (men 1.3 SD 0.6 mumol, women 1.1 SD 0.4 mumol) was lower (p less than 0.01) than that in the control group (men 1.8 SD 0.8 mumol, women 1.7 SD 0.8 mumol), but was reasonable in terms of recommended dietary allowances (1.2 mumol, 150 mg). Mean iodide content of local milk was 1.3 mumol/l. Any salt that is used in the home should continue to be iodised. However, it has become unnecessary in this population to use salt (ie, iodised salt) simply in order to avoid iodine deficiency, so long as other foodstuffs continue to contain iodine as at present. As the other sources of iodine may be subject to change, the adequacy of intake of iodine from these sources should be monitored from time to time in samples of the population.

Thyrotropin-induced acceleration of calcium efflux from mouse thyroid: evidence for inhibition by excess iodide.

Abstract: We investigated the effect of TSH on calcium transport in mouse thyroid, as well as the influence of iodide thereupon. Thyroid lobes were incubated in Krebs-Ringer bicarbonate buffer containing [45Ca2+] and the time-dependent uptake of [45Ca2+] by the lobes was observed. In the presence of 0.5 mU/ ml TSH, the uptake of [45Ca2+] was significantly depressed at early phases of incubation (from 20 to 40 min). Similarly, (Bu)2cAMP (DBC) depressed the [45Ca2+] uptake. The efflux of calcium was also studied by using thyroid lobes preloaded with [45Ca2+]. In the presence of 0.5 mU/ml TSH, [45Ca2+] release from the lobes was doubled in comparison with the control lobes incubated without TSH. DBC similarly accelerated [45Ca2+] release from the lobes. The acute administration of excess iodide to mice fed a low iodine diet inhibits the TSH-induced adenylate cyclase activation in thyroids. The acceleration of calcium efflux induced by TSH was completely abolished by the acute administration of excess iodide in thyroid...

Vascularization and iodide transport down regulation in rat goitre.

Abstract: This study was designed to investigate, in the rat, the regulation of the amount of thyroid iodide and of its organification during the involution of an experimentally induced goitre. The goitre was obtained by drastic iodine deficiency; male Wistar rats received an iodide deficient diet for 6 months, supplemented with PTU during the last 2 months. The study was followed for 16 days after the beginning of iodide refeeding (daily iodine intake = 50 micrograms). The thyroid iodide, total thyroid organic iodine and plasma iodide, PBI and TSH concentrations were determined from day 0 to 16 and compared to their control values (rats on a normal iodide diet for 6 months). In addition, a stereological study was carried out to determine if the extent of the gland vasculature might be implicated in the regulation of the thyroid iodide content. The plasma TSH concentration was very high and constant for 8 days (2.40 +/- 0.37 and 2.45 +/- 0.43 on day 0 and 8 respectively vs 0.25 +/- 0.12 microgram/ml in control rats), whereas iodination and secretion were blocked for 4 days (0.34 +/- 0.19 and 0.5 +/- 0.1 on day 0 and 4 respectively vs 14.4 +/- 2.0 micrograms 127I/gland in control rats) (Wolff-Chaikoff effect). Thyroid iodide amount increased enormously for 2 days (2.5 +/- 0.6 and 2.45 +/- 0.55 respectively on day 1 and 2 vs 0.09 +/- 0.01 micrograms 127I/gland on day 0), then strongly decreased between 2 and 4 days (1.15 +/- 0.27 127I/gland).(ABSTRACT TRUNCATED AT 250 WORDS)

New hydrometallurgical process for obtaining mercury from cinnabar ore

Abstract: A new hydrometallurgical process is presented for obtaining mercury from cinnabar concentrates. The process consists basically of three successive stages. Cinnabar is leached with hydrochloric acid-potassium iodide solution, and the H2S generated in the reaction is removed from the reaction vessel by an air flow. The leaching stage is followed by electrolytic treatment of the acid tetraiodomercuriate solution, obtaining very pure metallic mercury on the cathode and iodine on the anode. The iodine remains in solution if an excess of iodide ions is present as the insoluble I3- complex. The spent electrolyte is treated with the H2S produced in the leaching reaction to regenerate the iodide ions and the acid. Thus, in the regenerated solution all the reagents have the same concentration as at the beginning and may be recycled. Power consumption is less than 1 kilowatt-hour per kilogram of mercury.

Changes in thyroid function and serum iodine levels after prepartum use of a povidone-iodine vaginal lubricant.

Abstract: To determine if application of iodide to vaginal mucosa of pregnant women results in significant iodide absorption or changes in thyroid function, we studied 18 intrapartum women for whose examinations during labor povidone-iodine gel was used as a lubricant and 16 for whose examinations an iodine-free lubricant was used. Both serum inorganic iodine and total serum iodine increased significantly (p less than 0.001) after iodide exposure and fell (p = 0.003) to near baseline within two days. In both groups, serum thyroxine and triiodothyronine fell during labor and delivery; differences between groups were not significant. In the iodine-treated group, however, there was a significant increase in thyroid-stimulating hormone at two days postpartum (p less than 0.001). Iodide applied to vaginal mucosa of pregnant women is absorbed and affects the maternal pituitary-thyroid axis.

Automatic methods for the determination of total inorganic iodine and free iodide in waters

Abstract: Methods for the determination of total inorganic iodine and free iodide, based on the catalytic effect of iodide on the destruction of the thiocyanate ion by the nitrite ion, have been developed and automated. These methods use a Technicon AutoAnalyzer system, and a throughput of 20 samples per hour was achieved. Results obtained for a range of United Kingdom drinking waters showed that the total inorganic iodine method had a coefficient of variation of the order of 3%, a detection limit of 0.2 µg l–1 of l and a recovery of added iodine of 90–108%. The free iodide method had a coefficient of variation of the order of 10%, a detection limit of 0.4 µg l–1 of l and a recovery of added iodine of 89–109%. The effects of possible interfering substances on both methods have been investigated and shown to be negligible for normal drinking waters. The stability of dilute iodine solutions stored in containers made of different materials has also been evaluated.