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At least 19 recordsLinked to original sources
PubMed1986

Radiolytic breakdown of sodium iodide (131I) in sodium iodide (131I) capsules.

Sodium iodide (131I) capsules are widely used for both diagnosis and therapy. The radiochemical purity of both diagnostic and therapeutic capsules in use in Australia was studied by gel chromatography, high voltage electrophoresis and paper chromatography. It was found that in two of the three bands of therapeutic capsules examined, significant quantities of a labelled high molecular weight component was produced with the result that these capsules failed to meet British Pharmacopoeia, BP, and United States Pharmacopoeia, USP, requirements for radiochemical purity well before their quoted expiry time. The nature of the impurity has not been identified but it is thought to be either iodinated gelatin or an iodinated capsule component.

Capsules↗
PubMed1992

A routine method for using sodium iodide to stabilize sodium pertechnetate [99Tcm] dispensed for the preparation of 99Tcm-exametazime.

When preparing 99Tcm-exametazime, it is important to use sodium 99Tcm-pertechnetate that is less than 2 h old. The addition of sodium iodide (NaI) to 99Tcm-pertechnetate is known to extend this time to 6 h. This paper describes a technique for implementing this in routine practice. Sterile kits consisting of 440 micrograms NaI and 1.0 ml sodium chloride injection in a vial with a nitrogen atmosphere were prepared and stored at room temperature, 4 degrees C and -22 degrees C. Titrimetric analysis of iodide showed that under each storage condition, kits were stable for 8 weeks. To determine the effectiveness of the kits, the radiochemical purity (RCP) of 99Tcm-exametazime was measured by high-performance liquid chromatography (HPLC). The validity of this technique was determined by simultaneous analysis with the conventional thin-layer/paper chromatography (TLC/PC) technique on 24 occasions, over a range of RCP (94.5-54.6%). Radiochemical purities measured by HPLC and TLC/PC were 81.2 +/- 10.2 and 81.5 +/- 10.5%, respectively, and did not differ significantly (P greater than 0.30). The correlation between the techniques was high (r = 0.98). 99Tcm-exametazime was prepared using 1 h-old 99Tcm-pertechnetate, 6 h-old 99Tcm-pertechnetate and 6 h-old 99Tcm-pertechnetate dispensed in a NaI kit. At the recommended expiry time for this radiopharmaceutical, i.e. 30 min after preparation, RCPs were found to be 88.4 +/- 2.4, 80.9 +/- 2.0 and 89.3 +/- 3.0%, respectively (n = 5 for each technique).(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Stability↗
PubMed2004

Lack of correlation for sodium iodide symporter mRNA and protein expression and analysis of sodium iodide symporter promoter methylation in benign cold thyroid nodules.

Cold thyroid nodules (CTNs) are characterized by a reduced iodide uptake in comparison to normal thyroid tissue. The sodium iodide symporter (NIS) is the first step in thyroid hormone synthesis and mediates the active iodide transport in the thyroid cells suggesting that decreased iodide uptake could be a result of changes in NIS expression or molecular defects in the NIS gene. In contrast to previous studies, an intraindividual comparison of NIS mRNA expression in CTNs and their corresponding surrounding tissue was performed using direct detection of NIS mRNA. A significant reduction in NIS mRNA expression was detected in 86% of the 14 investigated CTNs. We hypothesized that human sodium iodide symporter (hNIS) transcriptional failure could be caused by primary molecular NIS gene defects and/or methylation of DNA in the NIS promoter. However, no mutation in the NIS cDNA nor in the NIS promoter region upstream up to-443 bp from the ATG start codon was detected. Therefore, primary molecular NIS gene defects were excluded. However, in 50% of CTNs with reduced NIS mRNA expression, the promoter region was hypermethylated. NIS mRNA expression in these hypermethylated CTNs only reached a maximum of 30% of the corresponding surrounding tissue. Hence, methylation of CpG islands in the NIS promotor could be a regulatory mechanism of NIS transcription in CTNs. Immunoblot revealed absent hNIS protein expression in the total cell membrane fraction in 45% of investigated nodules. In the majority of the remaining CTNs NIS protein expression was decreased in the nodule tissue compared to the corresponding surrounding tissue. For investigating protein expression immunhistochemistry has two advantages. First, the whole nodule area can be investigated, and second, NIS expression can be detected in areas where an immunoblot of a cell membrane fraction is negative. Interestingly, immunhistochemistry revealed higher NIS expression in 50% of CTNs compared to their corresponding surrounding tissues and NIS staining was predominantly intracellular. These data demonstrate that NIS protein expression does not reflect NIS mRNA expression. Therefore, factors that affect targeting of NIS to the plasma membrane are likely to be affected.

Blotting, Western↗
PubMed2003

The rat sodium iodide symporter gene permits more effective radioisotope concentration than the human sodium iodide symporter gene in human and rodent cancer cells.

Expression of the sodium iodide symporter (NIS) gene in tumor cells may provide a novel mechanism for treating cancer. The NIS mediates the normal physiological transport of iodide across the thyroid cell membrane. This mechanism of iodide uptake has been used to both diagnose and treat thyroid cancer. Tissue expression of the NIS is largely limited to the thyroid; therefore, expression of the NIS gene in cancer cells would allow for specific iodine uptake, radioisotope accumulation, and treatment. In this study, we directly compared the human and rat NIS (rNIS) for their ability to concentrate radioisotope into human and rodent cancer cells. Perchlorate-sensitive (125)I uptake in multiple cell lines was demonstrated following transduction with retroviral vectors expressing either the human or rNIS gene. Surprisingly, iodine uptake was consistently higher with the rNIS gene, up to 5-fold greater, when compared to the human gene, even within a variety of human tumor cell lines. This iodine uptake allowed for cell killing following (131)I treatment in NIS-transduced cells when assayed by in vitro clonogenic assays. These results demonstrate that the rNIS gene provides superior iodine uptake ability, and may be preferable for use in designing anticancer gene therapy approaches.

Animals↗
PubMed2004

Relative potencies and additivity of perchlorate, thiocyanate, nitrate, and iodide on the inhibition of radioactive iodide uptake by the human sodium iodide symporter.

The presence of perchlorate (ClO(4) (-)) in some U.S. drinking water supplies has raised concern about potential adverse thyroidal health effects, because ClO(4) (-) is known to competitively inhibit iodide uptake at the sodium iodide symporter (NIS). Humans are nutritionally and environmentally exposed to other competitive inhibitors of iodide uptake, including thiocyanate (SCN(-)) and nitrate (NO(3) (-)). The joint inhibiting effects of these three anions was studied by exposing Chinese hamster ovary cells stably expressing human NIS to varying concentrations of each anion separately, and in combination, and conducting measurements of (125)I(-) uptake. The entire data set was fit to a single Hill equation using maximum likelihood. The relative potency of ClO(4) (-) to inhibit (125)I(-) uptake at the NIS was found to be 15, 30 and 240 times that of SCN(-), I(-), and NO(3) (-) respectively on a molar concentration basis, with no evidence of synergism. These results are consistent with a common mode of action by these anions of simple competitive interaction, in which a concentration of any one of ClO(4) (-) SCN(-), and NO(3) (-), occurring either individually or as part of a mixture of the three anions, is indistinguishable from a concentration or dilution of either one of the remaining two ions in inhibiting iodine uptake at the NIS.

Algorithms↗
PubMed2000

A novel V59E missense mutation in the sodium iodide symporter gene in a family with iodide transport defect.

Iodide transport defect results from the malfunction of iodide transporter (sodium iodide symporter [NIS]), and is characterized by low uptake of iodide into thyroid cells. Genetic analysis revealed that a T354P missense mutation causes iodide transport defect in the homozygous state and is a frequent mutation in the Japanese population. We recently reported three siblings with iodide transport defect harboring the T354P mutation in the heterozygous state. Here we report a novel V59E missense mutation associated with these siblings. The mutant protein showed low iodide transport activity.

Adult↗
PubMed2004

[The practical relevance of the sodium iodide symporter].

The sodium iodide symporter (NIS) is an intrinsic plasma membrane protein mediating the active transport of iodide in the thyroid gland and a number of extrathyroidal tissues, in particular in the lactating mammary gland. Because of its crucial role for the ability of thyroid follicular cells to trap iodide, cloning of NIS opened up an exciting and extensive new field of thyroid-related research. Cloning and molecular characterisation of NIS allows investigation of its expression and regulation in thyroidal and non-thyroidal tissues and its potential pathophysiological and therapeutic implications in benign and malignant thyroid disease. In addition to its key function in thyroid physiology, NIS-mediated iodide accumulation allows both diagnostic thyroid scintigraphy and the effective therapeutic application of radioiodine in benign and malignant thyroid disease. Characterisation and application of NIS as a novel therapeutic gene for cytoreductive gene therapy of extra-thyroidal tumours and the presence of high endogenous NIS expression in the majority of breast cancers further suggest a promising role of NIS in the diagnosis and treatment of cancer outside the thyroid gland.

Gene Transfer Techniques↗
PubMed1999

Development of reverse transcription-competitive polymerase chain reaction method to quantitate the expression levels of human sodium iodide symporter.

The sodium iodide symporter (NIS) is the plasma membrane protein that mediates active iodide uptake into thyroid follicular cells. To investigate whether human NIS (hNIS) mRNA levels in papillary thyroid carcinomas (PCs) correlate with the ability of tumors to concentrate radioiodide, we developed a reverse transcription-competitive polymerase chain reaction (RT-cPCR) method to quantify the hNIS mRNA levels in thyroid tissues. We studied 7 normal thyroid tissues, 8 PCs, and 1 follicular adenoma. hNIS mRNA levels in PCs were generally lower than those found in normal thyroid tissues. The reduced radioiodide concentrating activity of PCs is due, at least in part, to the reduced expression and/or the decreased stability of hNIS mRNA.

Adenoma↗
PubMed2000

Reestablishment of in vitro and in vivo iodide uptake by transfection of the human sodium iodide symporter (hNIS) in a hNIS defective human thyroid carcinoma cell line.

Uptake of iodide is a prerequisite for radioiodine therapy in thyroid cancer. However, loss of iodide uptake is frequently observed in metastasized thyroid cancer, which may be explained by diminished expression of the human sodium iodide symporter (hNIS). Strategies to restore iodide uptake in thyroid cancer include the exploration of hNIS gene transfer into hNIS defective thyroid cancer. In this study, we report the stable transfection of a hNIS expression vector into the hNIS defective follicular thyroid carcinoma cell line FTC133. Stablely transfected colonies exhibited high uptake of Na125I, which could be blocked completely with sodiumperchlorate. hNIS mRNA expression corresponded with iodide uptake in semiquantitative polymerase chain reaction. Iodide uptake was maximal after 60 minutes, whereas iodide efflux was complete after 120 minutes. hNIS transfected FTC133 and control cell lines injected subcutaneously in nude mice formed tumors after 6 weeks. Iodide uptake in the hNIS transfected tumor was much higher than in the nontransfected tumor, which corresponded with hNIS mRNA expression in tumors.

Adult↗
PubMed2004

Dynamic iodide trapping by tumor cells expressing the thyroidal sodium iodide symporter.

The thyroidal sodium iodide symporter (NIS) in combination with various radioactive isotopes has shown promise as a therapeutic gene in various tumor models. Therapy depends on adequate retention of the isotope in the tumor. We hypothesized that in the absence of iodide organification, isotope trapping is a dynamic process either due to slow efflux or re-uptake of the isotope by cells expressing NIS. Iodide efflux is slower in ARH-77 and K-562 cells expressing NIS compared to a thyroid cell line. Isotope retention half times varied linearly with the number of cells expressing NIS. With sufficient NIS expression, iodide efflux is a zero-order process. Efflux kinetics in the presence or absence of perchlorate also supports the hypothesis that iodide re-uptake occurs and contributes to the retention of the isotope in tumor cells. Iodide organification was insignificant. In vivo studies in tumors composed of mixed cell populations confirmed these observations.

Animals↗
PubMed2003

Enhanced iodide transport after transfer of the human sodium iodide symporter gene is associated with lack of retention and low absorbed dose.

Transfer of the sodium iodide symporter (hNIS) has been proposed as a new principle of cancer gene therapy. Using clinically relevant doses of (131)I for the treatment of NIS-expressing prostate carcinoma cells, we investigated the kinetics and the absorbed doses obtained in these tumors. hNIS-expressing cell lines accumulated up to 200 times more iodide when compared to wild-type cells. However, a rapid efflux of the radioactivity (80%) occurred during the first 20 min after replacement of the medium. In rats, the hNIS-expressing tumors accumulated up to 20 times more iodide when compared to contralateral transplanted wild-type tumors. After 24 h and doses of 550, 1200 or 2400 MBq/m(2) hNIS-expressing tumors lost 89, 89 and 91% of the initial activity, respectively. Dosimetric calculations showed that 1200 MBq/m(2) resulted in 3+/-0.5 Gy (wild-type tumor 0.15+/-0.1 Gy) and 2400 MBq/m(2) resulted in 3.1+/-0.9 Gy (wild-type tumor 0.26+/-0.02 Gy). Although transduction of the hNIS gene induces iodide transport in rat prostate adenocarcinoma a rapid efflux occurs, which leads to a low absorbed dose in genetically modified tumors. With regard to a therapeutic application additional conditions need to be defined leading to iodide trapping.

Absorption↗
PubMed2004

The sodium-iodide symporter.

The sodium-iodide symporter (NIS) is an intrinsic plasma membrane protein that mediates active transport of iodide in the thyroid gland and several other extra-thyroidal tissues. This activity has been utilized for many years for imaging the thyroid gland and for treatment of thyroid disease both benign and malignant. Cloning and characterization of NIS has more recently allowed research into its use in non-thyroidal cancers through gene transfer for both diagnosis and treatment.

Animals↗
PubMed2006

99mTc-pertechnetate uptake in hepatoma cells due to tissue-specific human sodium iodide symporter gene expression.

UNLABELLED: The sodium iodide symporter (NIS) gene could be used as an ideal reporter gene as well as a promising therapeutic gene. 99mTc-pertechnetate has proven to be more advantageous than 131I-iodide with respect to image quality, procedure and radiation dose in examination of thyroid uptake and scintigraphy. Herein, we investigated the feasibility of monitoring human sodium iodide symporter (hNIS) gene expression with 99mTc-pertechnetate in hepatoma cells (MH3924A) following tissue-specific expression. METHODS: MH3924A cells were stably transfected with the recombinant retroviral vector, in which hNIS cDNA was driven by murine albumin enhancer/promoter (mAlb) and coupled to hygromycin resistance gene using an internal ribosomal entry site. Functional NIS expression in hepatoma cells was confirmed by an 125I(-) uptake assay. The dynamic uptake and efflux of 99mTc-pertechnetate was determined both in vitro and in vivo. RESULTS: The 99mTc-pertechnetate was up to 254-fold higher in stably transfected MH3924A cells than in wild-type cells. However, the in vitro efflux of 99mTc-pertechnetate out of recombinant cells was rapid with a half-life of less than 2 min. Further, the in vivo studies yielded clear images and quantitative data of mAlbhNIS-infected tumor xenografts using 99mTc-pertechnetate and gamma camera. CONCLUSION: The current study demonstrates enhanced 99mTc-pertechnetate uptake in hepatoma cells in vitro and in vivo following tissue-specific gene transfer using a recombinant retrovirus with the albumin enhancer/promoter and the hNIS gene. It is feasible to monitor hNIS gene expression noninvasively and quantitatively using conventional gamma camera and 99mTc-pertechnetate.

Animals↗