127I Distribution Research Articles

DISTRIBUTION OF IODINE-127 IN MARINE ORGANISMS FROM COASTAL WATERS AROUND AOMORI, JAPAN.

We measured the concentrations and determined the distribution of the stable isotope 127I in the marine organisms. Marine fish were collected from the Pacific Ocean near Aomori, Japan. The mean 127I concentrations in the muscle of marine fish ranged from 0.67μgg-1-wet weight (ww) in cherry salmon to 0.84μgg-1-ww in fat greenling. Among the tissues measured, the muscle showed the lowest levels of 127I in all fish species. The highest 127I concentration in the tissues of marine fish was observed in the ovary of fat greenling. The mean 127I concentration in the of Japanese scallop ranged from 0.06μgg-1-ww in adductor muscle to 5.49μgg-1-ww in mid-gut gland. The 127I concentrations in seaweeds were 67μgg-1-dry weight (dw) in sea lettuce and 1783μgg-1-dw in kombu. Thus, the distribution of 127I concentration in marine organisms varied considerably depending on the tissue.

Iodine isotopes (129I and 127I) in the hydrosphere of Qinghai-Tibet region and South China Sea

The radioactive isotope 129I, with a half-life of 1.57 × 107 years, is widely used as a tracer to assess nuclear safety, to track environmental and geological events and to figure out the details of the stable iodine geochemical cycle. This work investigated the 129I and 127I distribution in water samples collected from the terrestrial (rivers, lakes and springs) and marine water systems (estuary and sea) in China. The measured 129I concentrations of (1–51) × 106 atoms/L and 129I/127I ratios of (0.03–21) × 10−10 shows the variability of 129I level in the water systems. The local permafrost and seasonal frozen environment play a key role in groundwater recharge in the Qinghai-Tibet region, which is reflected in the 129I distribution in surface water. The depth distribution of 129I in the water column of the South China Sea reflects the effluence of different currents. The results also indicate that the hydrosphere of China contains one to three orders of magnitude less 129I compared to those reported in Europe. Despite the large distance, the European nuclear fuel reprocessing facilities represent the major source of 129I in the hydrosphere of China through atmospheric transport. The contribution of the Fukushima nuclear accident to 129I levels in the hydrosphere of China was negligible.

Distribution of 127I and 129I in precipitation at high European latitudes

We here present the most extensive data set on the distribution of 127I and 129I in precipitation (rain and snow) covering the period 2000–2006 and European latitudes 55°N–68°N. Our results indicate a wide variation in the concentrations and fluxes of the two isotopes associated with generally higher values at near coastal sites compared to the inland ones. Total wet‐related annual deposition of 127I and 129I on Sweden and Denmark is estimated at about 1.2 × 109 g and 60 g respectively. The average annual 129I wet deposition accounts for <1% and <0.05% of the total annual gaseous and liquid, respectively, discharges from the Sellafiled and La Hague Facilities. The 127I annual wet deposition represents <1% of the estimated global oceanic iodine flux. Air mass trajectories suggest that events of enhanced 129I in precipitation are closely related to southwesterly weather fronts from regions of elevated concentrations.

Evidence of iodine storage within thyroid stroma after iodine treatment: imaging by secondary ion mass spectometry (SIMS) microscopy in goitrous tissue.

We measured the 127I distribution within tyroid tissue to find out where intrathyroid iodine was deposited during iodine treatment in eight Tunisian female patients (aged 33-58 yr) with endemic euthyroid goiter. Before surgery, five patients were treated during 6 months either by Lugol's solution (group 1: three patients) or by Lugol's and L-thyroxine (group 2: two patients). All patients remained euthyroid during the course of the treatment, which supplied 3.8 mg/day iodine. Three other patients did not receive Lugol's solution (control group). Secondary ion mass spectrometry microscopy was used to map 127-I quantitatively on thyroid sections. Specimens obtained at thyroid surgery were divided macroscopically into nodular and extranodular tissue and chemically fixed to preserve organified iodine. The iodine profile of patients in group 1 did not differ from that in group 2: large amounts of iodine were localized in thyroid follicles and stroma of both nodular and extranodular tissues. In the control group, iodine within stroma was found only in the extranodular tissue. Despite the limited number of patients studied, these data suggest that stromal iodine might represent a storage compartment in times of large iodine supply.

Content and heterogeneity of distribution of iodine in human and bovine thyroid glands determined by neutron activation analyses.

While performing activation analytical investigations on the actual concentration of the long-lived radioactive 129iodine in human and bovine thyroid glands the absolute natural nonradioactive 127 iodine content was determined. In all thyroid glands an uneven distribution of 127I was found (in human thyroids from 0 to 0.75 micrograms 127I /mg, in bovine thyroids from 0 to 3.5 micrograms 127I /mg). The mean value of iodine concentration in human thyroid glands ranged from 230 micrograms/g to 490 micrograms/g. This is important because TSH independent autonomy is found at a cellular and follicular level during the development from diffuse to nodular goiter. Both processes may, however, not be related to each other. The resolution of the method used in our study is between the microscopic and the scintigraphic level with an accuracy of +/- 1%, and it shows an intermediate heterogeneity of iodine in thyroid glands.

Iodoamino acid distribution in the thyroid of rats on different iodine intakes and with normal plasma protein bound iodine.

ABSTRACT Groups of rats were fed a low iodine diet, or the same diet supplemented with known amounts of iodine. About 2–3 weeks later radioiodine (*I) was injected and the rats were killed on the next day or at different daily intervals after »blocking« with KClO4 and withdrawal of I supplements. Most of the animals had normal thyroid weights and plasma PBI. A few groups of rats were in a mildly iodine deficient state. The patterns of *I and 127I distribution among thyroidal iodine containing compounds was determined. It was found that these patterns were not the same in all thyroids with normal weights. Thus the pattern changed slightly but gradually concomitantly with the iodine intake and/or the thyroidal iodine content: The M*IT/D*IT2)3), MIT/DIT and T3*/T4* ratios decreased as the iodine intake and/or thyroidal iodine content increased. A decrease in the thyroidal I stores after pre-labelling of the thyroidal I-containing compounds also resulted in the same changes in the *I distribution pattern. Normal thyroids containing the same amount of iodine have similar iodoamino acid composition. The present data show that the iodoamino acid composition of the normal thyroid is affected by the availability of iodine, though to a lesser degree than that of I-deficient glands.

Thyroidal Iodoproteins in Pendred's Syndrome

ABSTRACT The distribution of 127I, 125I, or 131I, and protein was studied in thyroid tissue from 3 patients with Pendred's syndrome. In each of these patients a significant amount of trapped iodide was dischargeable after administration of perchlorate. Two specimens (nodular and paranodular tissue) were studied from each patient. Iodinated insoluble protein comprised 6.4–33.1% of the total radioactive iodine in the homogenates. More participate labeled iodine was present in the nodular tissue, per g of tissue, as compared to paranodular tissue. Nearly ⅓–½ of the total 127I was incorporated into the particulate protein. The pattern of protein distribution followed closely that of stable iodine. In the nodular tissue it was found that the insoluble protein had more labeled iodine per μg of 127I than in the soluble fraction. After 3 weeks of a tracer dose the particulate protein had more labeled iodine per g than after 24 hr of labeling. The particulate iodoprotein was solubilized with trypsin and could be s...

Mechanism of the suppression by iodide of the thyroidal 131-I release rate in the rat.

Yamada et at. (1) reported that the administration of KI decreased the thyroidal 131I release rate of the rats receiving moderate doses of propylthiouracil (PTU) (5 mg/day or less) to block recycling of radioiodide. It had no effect when the rats received 30 mg PTU/day, though the half-life of thyroidal 13lI was the same in both cases. These findings are confirmed here. It is moreover shown that in the first case the injection of KI results in an increased synthesis of iodothyronines, but not in the case of rats on the higher PTU doses. Estimation of thyroidal 131I release rates, intrathyroidal 127I distribution among iodine-containing compounds, plasma PBI and plasma and pituitary TSH activities in animals receiving an injection of stable iodide while the thyroid was being blocked with C1O4- or with PTU support the following interpretations: The thyroidal 131I release rate of rats receiving either high or low doses of PTU reflects an intensely increased, and not a normal, degree of TSH stimulation (2-5)....

Effects of structure and iodine content of the rat thyroid on the distribution of 127-I and 131-I between particulate and soluble thyroidal protein-bound iodine.

The distribution of 127I between particulate and soluble iodoproteins and the labeling of these 2 PBI fractions with 131I were studied in rat thyroids whose structure, function and iodine content were manipulated by hypophysectomy, feeding of a low iodine diet, administration of goitrogens such as propylthiouracil (PTU) or NaClO4, and feeding of diets rich or poor in iodine during recovery from NaClO4 treatment. The percentage of thyroidal PB127I in particulate form, which is around 10 in normal rats on an iodine-sufficient or iodine-deficient diet, was lowered to 2.6 in the iodine-rich, atrophic glands of hypophysectomized rats; in hyperplastic glands, whose iodine concentration was low, it ranged from 5.5 to 17.4, showing no correlation with the degree of hyperplasia or the iodine content. Both in hypophysectomized and in iodine-deficient intact rats, the percentage of thyroidal PB131I in the particulate fraction leveled off at 5-7 within 4 hr after 131I injection, in spite of marked differences in thyr...