Radioactive Isotopes Of Iodine Research Articles

気体状放射性ヨウ素（｀１２５´Ｉ）濃度の簡易測定法

Radioactive iodine isotopes are necessary to be handled carefully, because they scatter easily. As air concentration limits of the radioisotopes are very low levels, we should prepare the measurement technique using a large-volume aspirator and largescale equipments for environment measurement in radiation controlled areas. In the present study, we designed and manufactured a simple set of holder and charcoal filter connected to a foot pump, and we examined the validity of the system. The collecting efficiency of airborne iodine-125 by this system was 0.379±0.107. However, in the case that 10 L air were filtered by this system and counted for 10 min by a NaI (Tl) well-type scintillation counter, it was shown that iodine-125 at air concentration limit could be measured.

Safety Assessment of the Protective Gases Used in IFE Chambers

Using xenon as a fill gas in IFE chambers results in generating a large amount of radioactive xenon, iodine, and cesium isotopes. The cesium isotopes, 134Cs and 136Cs, and the iodine isotope, 126I, would produce a high level of off-site dose (62.13 rem) at the plant site boundary if they were released entirely to the environment during an accident. The xenon gas is pumped out of the chamber (recycled) during operation to remove unburned T2 and D2. Removing the Cs and I isotopes from the Xe gas during this recycling process will reduce the Cs and I inventories inside the chamber to negligible values. This process limited the off-site dose caused by the accidental release of Xe from the chamber of the SOMBRERO power plant to 29.9 mrem, which is less than the 1 rem no-evacuation limit. Using krypton, argon or neon as fill gases will result in producing lower levels of off-site dose than xenon.

In vivo imaging of herpes simplex virus type 1 thymidine kinase gene expression: early kinetics of radiolabelled FIAU.

Previous studies have shown that the herpes simplex virus type 1 thymidine kinase gene (HSV1-tk), in combination with appropriate radiolabelled substrates (e.g. [I*]-2'-fluoro-2'-deoxy-5-iodo-1-beta-D-arabinofuranosyluracil, I*-FIAU, where the asterisk indicates that any of the various radioactive iodine isotopes can be used), can be used as a reporter gene for in vivo monitoring of gene transfer and expression. The aim of our study was to examine the early kinetics of I*-FIAU and the possibility of utilising iodine-123-labelled FIAU for imaging of gene expression. CMS-5 fibrosarcoma cells were transduced in vitro with the retroviral vector STK containing the HSV1-tk gene. BALB/c mice were inoculated subcutaneously with HSV1-tk(+) and tk(-) cells into both flanks. FAU (2'-fluoro-2'-deoxy-1-beta-D-arabinofuranosyluracil was radioiodinated (123I, 125I) using the iodogen method. High-performance liquid chromatography purification resulted in high specific activity and radiochemical purity for both tracers ([123I]FIAU and [125I]FIAU). Biodistribution studies and gamma camera imaging were performed at 0.5, 1, 2 and 4 h p.i. In addition, the genomic DNA of the tumours was isolated for measurement of the activity accumulation resulting from the [125I]FIAU incorporation. Biodistribution studies 0.5 h p.i. showed tumour/blood and tumour/muscle ratios of 3.8 and 7.2, respectively, for the HSV1-tk(+) tumours, and 0.6 and 1.2, respectively, for negative control tumours. Fast renal elimination of the tracer from the body resulted in rapidly increasing tumour/blood and tumour/muscle ratios which reached values of 32 and 88 at 4 h p.i., respectively. Tracer clearance from blood was bi-exponential, with an initial half-life of 0.6 h followed by a half-life of 4.6 h. The tracer half-life in herpes simplex viral thymidine kinase-expressing tumours was 35.7 h. The highest activity accumulation (20.3%+/-5.7% ID/g) in HSV1-tk(+) tumours was observed 1 h p.i. At that time, about 46% of the total activity found in HSV1-tk(+) tumours was incorporated into genomic DNA. Planar gamma camera imaging showed a distinct tracer accumulation as early as 0.5 h p.i., with an increase in contrast over time. These results suggest that sufficient tumour/background ratios for in vivo imaging of HSV1-tk expression with [123I]FIAU are reached as early as 1 h p.i.

The influence of low doses 131I-induced maternal hypothyroidism on the development of rat embryos

The aim of our research was to create and verify a model for studying the effects of a low dose of 131I and 131I-induced maternal hypothyroidism on the development of the embryo's thyroid gland and brain. The given dose (150 microCi) corresponds to the absorbed dose of 0.5 Gy. This dose is similar to that dose received by large numbers of the population of the C.I.S. regions polluted by radioactive isotopes of iodine as a result of the Chernobyl accident in 1985. Thirty-five female Wistar rats and their 168 newborn pups were used for observation. The females were divided into a control group and four experimental groups (each distinguished by the time of 131I injection: group I - no less than 12 days before mating; groups II, III and IV - on 5th, 10th and 16th days of gestation, respectively). In all the experimental female groups the incorporate dose of 131I led to hypothyroidism accompanied by a 43% reduction in the thyroxin level and by a nearly 8-fold increase in the TSH level. However, the influence of maternal hypothyroidism on the development of the thyroid gland and brain of embryos depends on the time when 131I took effect. There is a reduction in the weight of the newborns' brain and thyroid gland, total body mass. The hormonal status of the newborns' thyroid gland also changes. The proposed model will allow us to study many aspects of induced changes in the brain and thyroid gland of the embryos which develop under conditions of maternal hypothyroidism resulting from a low dose of 131I, administered at the critical times of development.

Clinicopathologic findings in recurrent choroidal melanoma after transpupillary thermotherapy

Objective This study aimed to report the clinicopathologic findings of recurrent choroidal melanoma after transpupillary thermotherapy (TTT). Design Two case reports. Methods The clinical histories and ophthalmologic findings of two patients with recurrent choroidal melanomas who did not respond to TTT were reviewed. Both patients had their eyes with the melanoma enucleated and processed routinely for light and electron microscopic examination. Main outcome measures The eyes were examined for histopathologic and ultrastructural findings. Results Histopathologic examination showed choroidal melanomas with extensive tumor necrosis and hemorrhage. In areas, tumor cells appeared histologically intact and presumably viable, with ultrastructural evidence of melanogenesis. The eye from one patient was treated only with TTT and showed hemorrhagic necrosis with cytolysis and no changes to tissues surrounding the melanoma. The eye from the other patient, treated with TTT and a radioactive isotope of iodine (I 125) plaque, exhibited areas of intact tumor, tumor necrosis, fibrosis, and radiation retinopathy. Conclusions These two cases among a total treated series of 14 patients represent examples of uveal melanoma regrowth after TTT. Opaque media precluded adequate treatment in the first case that showed some TTT effect. The second case showed a combination of TTT and I 125 effect and failed because of the aggressive nature of tumor.

Molecular genetics of childhood papillary thyroid carcinomas after irradiation: high prevalence of RET rearrangement.

Epidemiological studies have revealed a connection between thyroid carcinogenesis and a history of radiation. The molecular mechanisms involved are not well understood. It has been claimed that RAS, p53 or GSP mutations and RET or TRK rearrangements might play a role in adult thyroid tumors. In childhood, the thyroid gland is particularly sensitive to ionizing radiation. The reactor accident in Chernobyl provided a unique chance to study molecular genetic aberrations in a cohort of children who developed papillary thyroid carcinomas after a short latency time after exposure to high doses of radioactive iodine isotopes. According to the concepts of molecular genetic epidemiology, exposure to a specific type of irradiation might result in a typical molecular lesion. Childhood papillary thyroid tumors after Chernobyl exhibit a high prevalence of RET rearrangement as almost the only molecular alteration. The majority showed RET/PTC3 (i.e., ELE/RET rearrangements), including several subtypes. Less frequently, RET/PTC1 (i.e., H4/RET rearrangements), and a novel type (RET/PTC5, i.e., RFG5/RET) were observed. Proof of reciprocal transcripts suggests that a balanced intrachromosomal inversion leads to this rearrangement. Breakpoint analyses revealed short homologous nucleotide stretches at the fusion points. In all types of rearrangement, the RET tyrosine kinase domain becomes controlled by 5' fused regulatory sequences of ubiquitously expressed genes that display coiled-coil regions with dimerization potential. Oncogenic activation of RET is apparently due to ligand-independent constitutive ectopic RET tyrosine kinase activity. The analysis of this cohort of children with radiation-induced thyroid tumors after Chernobyl provides insights into typical molecular aberrations in relation to a specific mode of environmental exposure and may serve as a paradigm for molecular genetic epidemiology.

Microwave Thermoradiotherapy for Uveal Melanoma: Results of a 10-year Study

Objective: The purpose of the study is to evaluate clinically the use of microwaveheating (hyperthermia) as an adjuvant to ophthalmic plaque irradiation for treatment of patients with uveal melanoma. Hyperthermia was also used as a radiation sensitizer, allowing for significant dose reductions during ophthalmic plaque radiation therapy.Participants: In this case series, 48 patients were treated with microwave plaque thermotherapy for uveal melanoma.Intervention: Microwave treatment, which involved affixing a miniature microwave dish antenna on the sclera beneath the tumor after completion of plaque brachytherapy, was performed. During hyperthermia treatment, the tumor's apex was targeted to receive a minimum of 42 °C for a 45-minute duration. A subset of 38 (79%) were given reduced apical doses of ophthalmic plaque radiation (radioactive isotope of iodine [125I] or palladium-103 [103Pd]) to an average of 52.6 Gy.Main Outcome Parameters: Patients were evaluated for visual function, microwave toxicity, radiation oculopathy, eye retention, local tumor control, and metastatic disease.Results: Patients have been observed for up to 10 years and for an average of 60 months (5 years). To date, there have been 3 cases of postoperative tumor enlargement (growth) for a 93.8% local control rate. Two patients were lost to followup. Seven eyes have been enucleated: three due to neovascular glaucoma, one due to uveitic neovascular glaucoma, and three due to progressive tumor enlargement. Although 15 patients have died, only 4 deaths were because of metastatic choroidal melanoma. Of the original 48 patients, 33 (69%) have maintained within 2 lines or have better than their preoperative visual acuity. Side effects attributable to heating have included decreased intraocular pressure without hypotony as well as chorioretinal scar formation within and around the targeted zone.Conclusions: The results of this series suggest that adjuvant microwave thermotherapy can be used with reduced doses of ophthalmic plaque radiation therapy to control the growth of uveal melanomas. Although the incidence of neovascular glaucoma, enucleation, and tumor regrowth is comparable to that of other series evaluating radiation alone, the visual acuities of microwave plaque the rmotherapy-treated eyes were found to be superior.

La protection de la thyroïde de l'enfant et du fœtus en cas d'accident nucléaire

The administration of stable iodine in order to keep the thyroid gland away from radioactive iodine isotope contamination has long been regarded with caution by the health authorities, mainly because of the potential toxicity of iodine in newborns, young children and adults with thyroid pathology. Therefore, the risk of oral stable iodine given for a limited period of time must be compared to the risk of cancer due to radioactive exposure. The analysis of complications following the nuclear accidents of Marshall Islands in 1954 and Tchernobyl in 1986 has shown that newborn infants and young children have the highest risk, the main complications being cancer (papillary carcinoma) and hypothyroidism. In the most exposed areas of Bielorussia, the incidence of child thyroid cancer has been approximately multiplied by 100. On the other hand, studies of children from Utah who were contaminated after nuclear tests in the Nevada desert have shown that following mild iodine radioactive exposure, the risk is not significant. Among complications attributed to stable iodine, only those related to an oral intake over a limited period of time should be considered. On the basis of nuclear medicine experience and scientific literature, the risk can be considered as negligible in adults but not in children. However, the Polish experience in children has reported a low risk and only benign complications, mainly transient hypothyroidism. Thus from current knowledge, it appears that the potent risks linked to stable iodine administration should not contraindicate the collective preventive stable iodine administration in case of nuclear accident.

Potassium iodide for thyroid blockade in a reactor accident: administrative policies that govern its use.

A marked increase in thyroid cancer among young children who were in the vicinity of the Chernobyl nuclear power plant at the time of the 1986 accident strongly suggests a possible causal relationship to the large amounts of radioactive iodine isotopes in the resulting fallout. Although remaining indoors, restricting consumption of locally produced milk and foodstuffs, and evacuation are important strategies in a major breach-of-containment accident, stable potassium iodide (KI) prophylaxis given shortly before or immediately after exposure can reduce greatly the thyroidal accumulation of radioiodines and the resulting radiation dose. Concerns about possible side effects of large-scale, medically unsupervised KI consumption largely have been allayed in light of the favorable experience in Poland following the Chernobyl accident; 16 million persons received single administrations of KI with only rare occurrence of side effects and with a probable 40% reduction in projected thyroid radiation dose. Despite the universal acceptance of KI as an effective thyroid protective agent, supplies of KI in the US are not available for public distribution in the event of a reactor accident largely because government agencies have argued that stockpiling and distribution of KI to other than emergency workers cannot be recommended in light of difficult distribution logistics, problematic administrative issue, and a calculated low cost-effectiveness. However, KI in tablet form is expensive and has a long shelf life, and many countries have largely stockpiles and distribution programs. The World Health Organization recognizes the benefits of stable KI and urges its general availability. At present there are 110 operating nuclear power plants in the US and more than 300 in the rest of the world. These reactors product 17% of the world's electricity and in some countries up to 60-70% of the total electrical energy. Almost all US nuclear power plants have multistage containment structures with large steel and concrete shells and multiple redundancy of core cooling mechanisms. These successfully prevented the release of major amounts of radionuclides in the Three Mile Island partial loss-of-primary coolant accident in 1979. The Chernobyl accident, in a different type of reactor that is common in Eastern Europe, did not have effective outer shell containment and released almost 50 MCi of 131I compared to the 20 Ci of 131I released at Three Mile Island. Such accidents have precipitated extensive re-evaluation of the design and safety devices of all operating reactors. However, a major contributing factor to the accidents was human error and considerable efforts must be made to train plant operators so they have a better understanding of reactor operation and use of safety mechanisms.

Labeling of insulin with non-radioactive 127I and application to incorporation of radioactive 125I for use in receptor-binding experiments by high-performance liquid chromatography

Conditions for the labeling of insulin with radioactive iodine isotopes were investigated by means of incorporation of non-radioactive 127I into the peptide. Either the chloramine-T (CT) or lactoperoxidase-hydrogen peroxide (LPO) technique was applied and reversed-phase high-performance liquid chromatography (RP-HPLC) was used for analysis of the reaction products. The LPO method provided the 127I-labeled peptide within 15–30 min, whereas the CT alternative yielded the labeled substrate even within 15 s. However, the latter reaction can only be controlled in a reproducible manner with difficulty and undesirad side-reactions became increasingly prominent when t a few seconds. In another experiment, the LPO technique was applied for radiolabeling insulin with 125I. The product was first purified by size-exclusion chromatography (SEC) and then subjected to RP-HPLC. SEC yielded two peaks. The smaller one, which eluted at a slightly higher K d value (accounting for about 14% of total radioactivity) predominantly consisted of material eluting at the column's void volume under the conditions of RP-HPLC, whereas the main SEC fraction (accounting for about 86% of total radioactivity) yielded a single peak, as shown by HPLC. The radioactive material attributable to the main SEC fraction revealed the expected receptor-binding properties, as evidenced by displacement experiments with non-radioactive insulin, as well as the action of tetradecanoyl phorbol acetate on the binding characteristics and thus indicating formation of a labeled hormone retaining biological activity.

Radioimaging of human breast carcinoma xenografts in mice by [ 123I]-labeled Z-17α-iodovinyl-11β-chloromethyl-estradiol

Z-17α-iodovinyl-11β-chloromethyl-estradiol (Z-CMIV), a new selective estradiol derivative, can easily be labeled with high efficiency by radioactive iodine isotopes. Biodistribution studies and quantitative scintigraphic imaging of human breast carcinoma xenografts in mice demonstrated continuous and selective accumulation of the [ 123I]Z-CMIV, in estrogen receptor (ER)-positive target tumors, with significantly high target/nontarget ratio up to 48 h post-injection. A receptor-mediated mechanism of concentration of Z-CMIV in target tissues was confirmed by scintigraphic imaging and by biodistribution studies.

Radiation Exposure and other Factors that Predispose to Human Thyroid Neoplasia

Radiation exposure is the only known etiologic factor clearly associated with an increased risk of thyroid cancer. External beam radiation treatment for medical therapy, acute gamma ray exposure from environmental sources (nuclear weapons, nuclear power plant accidents), and ingestion of short-lived radioactive iodine isotopes are the primary sources of radiation exposure, which increases the risk of benign and malignant thyroid neoplasia. Relative risk is directly proportional to the exposure dose and is inversely proportional to the age at exposure.

Determination of gaseous and particulate129I in atmospheric air by neutron activation analysis

A method for determining129I in atmospheric air is presented. It consists of the following stages: sampling (of aerosol and gas fractions separately), preparation of a sample for irradiation in a reactor by a destructive distillation method, irradiation of samples in a reactor, radiochemical separation and130I activity measurements by slow coincidences. Iodine isotopes (including129I) in the atmospheric air have mostly been found in gas fractions (except132I). Gas compounds and percentages of radioactive and stable iodine isotopes coincide.

Radioiodine for the treatment of thyroid disease

Radioiodine (131I), a radioactive isotope of iodine, permanently suppresses thyroid function and is widely used in the UK for the treatment of patients with hyperthyroidism (thyrotoxicosis). It is used either as first-line treatment or when a patient has relapsed after thyroidectomy or an antithyroid drug. Radioiodine is also a standard part of treatment for some kinds of thyroid cancer.

Photoaffinity labelling of mitochondrial nadh: Ubiquinone reductase with pethidine analogues

1.Chemically reactive derivatives of pethidine analogues—novel potent inhibitors of the mitochondrial NADH : ubiquinone reductase (complex I)—were synthesized. 2. Dose-response curves of these components revealed that the photoactivatable aryl azido derivative has retained most of the inhibitory activity displayed by the parent substance. After introduction of a radioactive iodine isotope into the molecule, it was used as a probe for the localization of the inhibitor binding polypeptides within complex I. 3. Photolysis of the radiolabelled derivative bound to isolated complex I both from Neurospora crassa and beef heart resulted in a covalent incorporation of the inhibitor into 6–7 individual subunits of the enzyme. Essentially the same labelling patterns were obtained, when whole mitchondrial membranes were incubated with the reactive derivative. 4. Applying a double isotope labelling technique, the inhibitor-binding polypeptides in N. crassa were identified as mitochondrially synthesized constituents of complex I (ND gene products). In the beef heart enzyme the ND-1 product was detected to be among the polypeptides reacting with the inhibitor. 5. Competition experiments employing either NADH or decylbenzoquinone (DB), together with the pethidine analogue, showed that both enzyme substrates interfere specifically with the inhibitor binding to complex I.

Selectivity in the laser-induced photochemistry of iodine + acetylene in the gas phase

The reaction between I/sub 2/ and acetylene has been carefully studied to establish its potential use for the separation of radioactive isotopes of iodine. The two possible photoproducts, cis- and trans-1,2-diiodoethylene, were prepared and then characterized by GC, GC-MS, and FTIR in both condensed and gas phases. For the first time the IR spectra of both cis and trans isomers in the gas phase are reported. Below the dissociation energy, when either the ortho or para modifications of I/sub 2/ were excited, only the trans isomer was found as a product. Studies conducted with isotopic mixtures of /sup 127/I/sub 2/, /sup 129/I/sub 2/ and /sup 127/I, /sup 129/I revealed that the reaction proceeds by the addition of iodine atoms to acetylene. The production of atoms leads to isotopic scrambling. Consequently, this reaction cannot be used to separate the isotopes of iodine, as previously postulated.

Intense mass-separated beams of halogens and beta-delayed neutron emission from heavy bromine isotopes

Improved production yields of short-lived halogens were obtained from a ThO2 target, irradiated with 600 MeV protons, in combination with a negative surface ionization source. Mass-separated samples were studied by decay spectroscopy. Production yields of radioactive isotopes of chlorine, bromine, iodine and astatine are presented. Half-lives and relative neutron emission probabilities were measured for the heavy bromine isotopes89−92Br. Normalizing to earlier publishedPn values for89Br, the results are:89Br (4.30±0.14s,P n =13.6±0.8%),90Br (1.92±0.06s,P n =24.8±1.5%),91Br (0.53 ±0.03 s,P n =30.1 ±2.1%), and92Br (0.31 ±0.02 s,P n =34.6±2.5%). Energy spectra ofβ-delayed neutrons were measured.

14] In Vitro iodination of nucleic acids

Publisher Summary This chapter discusses in vitro iodination of nucleic acids. Nucleic acids can be labeled, with a radioactive isotope in vitro, by heating them in a mixture containing radioactive iodine and thallic trichloride (TlCl3). The reaction is rapid and simple, and results in the formation of a stable covalent bond between the radioactive iodine atom and carbon atom of cytosine in the nucleic acid. The biological properties of the nucleic acid are not significantly affected by this procedure. During iodination of nucleic acids, some of the radioactive iodine isotope becomes volatile. Radioactive contamination of the laboratory can be minimized by placing a gas-tight seal on the reaction container, by adding 125I to the mixture through the seal by means of a hypodermic syringe, and by withdrawing air from the sealed container by means of a syringe so that the inner pressure remains less than atmospheric even when the container is heated to 70°. Serum bottle stoppers, 13 × 20 mm, are suitable for 12 × 125 mm Pyrex glass test tubes and Burrell silicone seals are suitable for 4 × 50 mm Pyrex tubes.

DNA binding proteins in growing and resting young and senescent cultured chick fibroblasts

Total proteins of replicating and stationary phase early and late passage cultured chick fibroblasts have been labeled in vitro with radioactive isotopes of iodine. Protein preparations labeled with 125I and 131I were mixed together and the DNA binding proteins (DBP) isolated by chromatography on single stranded DNA covalently linked to Sepharose. Proportions of the various DBP were measured after electrophoresis of the double labeled DBP preparations on sodium dodecyl sulfate-polyacrylamide gels. Three major DBP were present at different proportions in actively dividing or resting early and late passage cells. The relative amounts of DBP of 92,000 and 175,000 daltons were identical in exponentially growing young and senescent fibroblasts. Both cultures were also similarly devoid of a 63,000 dalton protein. Comparison of the distribution of DBP in replicating and highly dense, stationary young cells revealed that the relative amounts of the species of molecular weights 92,000 and 175,000 were significantly reduced in resting cells whereas the proportion of the 63,000 dalton species was greatly increased in these cultures. By clear contrast, the DBP profile of resting, senescent cells which cease to divide at relatively low densities, was indistinguisable from that of actively dividing young or senescent fibroblasts. Thus, while arrest of growth of young cells is accompanied by distinct change in the proportions of several DBP, cessation of proliferation of old cultures does not involve such change.

Nephrotoxic and pneumotoxic antibodies and their acute action on lungs: III. Organ localization of antibodies after experimental administration of lethal doses

Experimental intravenous administration of large doses of heterologous anti-glomerular and anti-lung antibodies induces acute exsudative haemorrhagic changes in the lungs resulting in death of the experimental animals. The specific localization of these antibodies labelled with radioactive isotopes of iodine and administered using the paired-isotope technique with radioiodinated normal IgG, displayed high values in the lungs, liver and kidneys. Pulmonary changes developing after administration of the same dose of anti-glomerular antibodies into the left heart ventricle are of lesser extent and the animals survive. On this mode of administration, the specific localization of antibodies presents lower values in the lungs, whereas the values in the kidneys and liver are approximately the same as seen after intravenous administration. Antibody localization in the kidneys and liver is facilitated by the morphologic structure of the capillaries, whereas in the lungs a direct transendothelial transfer must be considered, since in this organ capillary endothelium forms a coherent layer. Attention is being drawn to the high specific localization of antibodies in the liver and to the potential effect of these antibodies on the liver.