Synthesis, radiolabeling and In Vivo tissue distribution of an anti-oestrogen glucuronide compound, (99m)Tc-TOR-G.

Toremifene (TOR) has been used as an anti-oestrogen drug for the treatment and prevention of human breast cancer. The aim of this study was the addition of the hydrophilic groups diethylenetriamine pentaacetic acid (DTPA) and glucuronic acid to the starting substance TOR and to label it with technetium-99m ((99m)Tc) radionuclide and to investigate radiopharmaceutical potential of the new compound. The synthesis reactions are completed in four steps, including enzymatic reaction, with the following substeps; preparation of microsomal fraction from Hutu 80 cell line and subsequent purification of UDP-glucuronyl transferase (UDPGT), estimation of protein quantity in microsomal samples and glucuronidation reaction. The results indicate that (99m)Tc-TOR-G may be proposed as a new anti-oestrogen glucuronide imaging agent for ovarian tumours.

131I labeling of tamoxifen and biodistribution studies in rats.

Tamoxifen [TAM ([Z]-2-[4-(1,2-diphenyl-1-di-butenyl)-phenoxy]-N,N-dimethylethanamine)] has been used as an antiestrogen drug for treatment and prevention of human breast cancer. Tamoxifen was labeled with 131I using iodogen as an oxidizing agent. Mass spectroscopy of the cold standard showed that the labeling occurs in ortho position to the phenyl ether position of TAM as expected. Quality control, radiochemical yield and stability were established using the radioelectrophoresis method. The radiolabeled compound maintained its stability throughout working period of 24 h. Scintigraphic imaging was performed and tissue distribution was determined in Albino Wistar rats. According to biodistribution and imaging experiments the radiolabeled compound presented estrogen receptor (ER) specificity and it was uptaken by endometrium as well as breast tissue.

Scintigraphic imaging with a peptide glucuronide in rabbits: 99mTc- exorphin C glucuronide.

A peptide glucuronide (Exorphin C glucuronide) was labeled with 99mTc using glucoheptonate (GH) as a bifunctional chelating agent. Scintigraphic imaging was performed in male Albino rabbits. Exorphin C glucuronide showed rapid and efficient labeling with 99mTc using glucoheptonate as a bifunctional chelate. Results demonstrated that 99mTc-GEG may be a useful new type of glucuronide derivative of peptides for diagnosis of some cancer diseases.

Synthesis of an estradiol glucuronide derivative and investigation of its radiopharmaceutical potential.

The aim of the current study was to synthesize a derivative of estradiol glucuronide, which is able to be labeled with 99mTc and to investigate its radiopharmaceutical potential using imaging and biodistribution studies. An estrogen derivative, beta-estradiol (1,3,5,[10]-estratriene-3,17beta-diol) attached to diethylenetriamine pentaacetic acid (DTPA) was synthesized in six steps. At the end of these steps a compound of estradiol and DTPA derivative called deoxy demethyl homoestradiolyl diethylenetriamine pentaacetic acid (ESTDTPA) was synthesized. Afterwards, this compound was reacted with UDP-glucuronyl transferase (UDPGT). Following the glucuronidation reaction, the product called deoxy demethyl homoestradiolyl diethylenetriamine pentaaceticacid-glucuronide (ESTDTPAG) was obtained. Synthesized products were purified using high performance liquid chromatography (HPLC). The identification of the purified products and impurities were also established using HPLC. Synthesized compound was labeled with 99mTc. Thin layer radio chromatography (TLRC) technique was used to determine their radiochemical yields and stabilities. Labeling yield was over 96%. The biodistribution studies were performed on female Albino Wistar rats. The activity per gram tissue was calculated and time-activity curves were plotted. The target organs (tumor, as well as uterus, ovaries, adrenals and other ER containing tissues) retain the estradiol derivative longer than nontarget organs, but even these lost most of their activity within a few hours. In addition, the imaging studies were performed on normal and tumor bearing female Albino Wistar rats using Camstar XR/T gamma camera. In gamma-scintigraphic imaging studies with 99mTc-ESTDTPAG the breast tumors could be well visualized up to 24 h.

Scintigraphic imaging with 99mTc- exorphin C in rabbits.

Exorphin C is a peptide with five amino acids [(Tyr-Pro-Ile-Ser-Leu) Trifluoroacetate salt] (Sigma) that has an affinity to opioid receptor-expressing tissues and tumors. Exorphin-C was labeled with 99mTc using glucoheptonate (GH) as bifunctional chelating agent. Then, we investigated its radiopharmaceutical potential as opioid receptor-expressing tissue on rabbits. Quality controls were performed by ITLC, paper electrophoresis and HPLC. Labeling efficiency was higher than 98%. The compound was stable for at least 5 h at room temperature. Scintigraphic imaging with 99mTc-GH-exorphin C (99mTc-GE) was performed on male Albino rabbits. Static images were obtained from anterior projection using a Camstar XR/T gamma camera at several time intervals. Although a significant amount of activity was seen in the brain, less activity was seen on receptor saturation studies at 30 min. Slight hepatobiliary excretion was seen, though the main excretion route was renal. After saturating, the receptor hepatobiliary excretion was not seen; the only excretion route was renal.

Stability of iodine content in iodized salt.

lodization of consumed salts is mandatory in many countries fighting against to iodine deficiency. In salts iodine stability is affected by storage conditions. In this study, stabilization of iodine in salt has been determined by using Isotope Dilution Analysis. Heating, heating with oxidizing agent, incubation by time were the parameters which have been determined. Iodine loss was 41.16% by heating at 200 degrees C up to 24 hours. When the iodized salt heated with oxidized agent iodine loss rose up to 58.46% in 24 hours. Iodine loss mechanism seems similar in both cases. However iodine loss is greater in the presence of H202. After the salt was stored at room temperature with a relative humidity of 30%-45% and in sealed paper bags for three years, 58.5% of iodine content lost in approximately 3.5 years.

New radiolabeled CCK-8 analogues [Tc-99m-GH-CCK-8 and Tc-99m-DTPA-CCK-8]: preparation and biodistribution studies in rats and rabbits.

The aim of this study is to label CCK-8 with Tc-99m and to investigate its radiopharmaceutical potential. CCK-8 was labeled with Tc-99m using GH and DTPA as bifunctional chelating agents. Labeling efficiency was higher than 99%. Complex was stable more than 5 hours at room temperature. 37 MBq Tc-99m-GH-CCK-8 or Tc-99m-DTPA-CCK-8 was administered intravenously to rabbits for biodistribution experiments. Dynamic and static images were obtained from anterior projection using a Camstar XC/T gamma camera. For quantitative evaluation, regions of interest were drawn on organs and time-activity curves were generated. The highest accumulation occurred in brain within 10 and 30 minutes after injection. Renal and hepatobiliary excretion were observed. Brain distribution studies in rats showed the highest activity was in hypothalamus. Results demonstrated that Tc-99m-GH-CCK-8 and Tc-99m-DTPA-CCK-8 analogs may be a useful new class of receptor-binding peptides for diagnosis and therapy of brain diseases related with CCK-B receptor-expressing tumors.

Detecting inflammation with 131I-labeled ornidazole.

The aim of this study was to demonstrate the accumulation of 131I-labeled ornidazole (131I-ORN) in experimental abscesses. 131I-ORN was prepared by electrophilic radioiodination of ORN, using radioiodide in the presence of Iodogen. An in vivo inflammation model was prepared by intramuscular injection of turpentine into the thigh of rabbits. Four days later 131I-ORN was intravenously administered to rabbits. Serial scintigrams were performed at different periods, using a Sophy DX Gamma Camera. 131I-ORN was visualized at 10 min after injection. 131I-ORN was also administered intraperitoneally to rats with turpentine-induced inflammation, for quantitative biodistribution studies. Counts of selected tissues were taken by a NaI(Tl) scintillation detector (gamma counter) after rats were decapitated. The target-to-non-target muscle ratios were 2.5, 2.6, 2.9 and 1.9 at 1, 3, 5 and 24 h, respectively.

Determination of iodide amounts in urine and water by isotope dilution analysis.

Urinary iodide and iodine in drinking water were determined in 318 healthy children aged 0 to 18 yr living in Izmir and environmental rural and urban areas in the western part of Turkey. The method is based on substochiometric isotope dilution analysis. Iodide was precipitated by substoichiometric amounts of AgNO3. Iodide-131 was used as a tracer. Electrophoresis was performed to separate Ag131I from excess 131I-. The Ag131I zone was cut off the electrophoresis paper and counted with a NaI(Tl) scintillation counter. Count rates were plotted versus added KI concentrations. The unknown iodide amount was found by using these linear plots. Iodide concentration ranges were within 1.8-100.45 micrograms/L in the analyzed drinking water samples. The mean value was 44.14 +/- 17.33 micrograms/L and the median was 58.08 micrograms/L. Urinary iodide concentration ranges were 0.22-142.22 micrograms/L. The median of the distribution was 37.71 micrograms/L and the mean was 40.30 +/- 24.05 micrograms/L. The results show that the examined area suffers moderate iodine deficiency.

Labeling of zopiclone with iodine-131.

Zopiclone (ZPC) was labeled with 131I by using the halogen exchange method. Temperature and reaction time effects to labeling yields were studied. Infrared, nuclear magnetic resonance, and gas chromatography-mass spectroscopy spectra were undertaken to identify chemical structure. High performance liquid chromatography (HPLC) was performed to determine purity of cold zopiclone. Biodistribution studies were performed on rabbits and rats. 131IZPC was administered intravenously to rabbits. Static images were taken by a Sophy DX Gamma Camera. 131IZPC was also administered intraperitoneally to rats. Activities were counted in a NaI(Tl) scintillation detector for several organs (liver, brain, spleen, lung, blood, fat) after rats were decapitated on different times. Biodistribution profiles were obtained depending on the time.

Labeling of penicillamine di sulfide with technetium-99m.

Complex forming conditions of Penicillamine di sulfide with 99mTc have been specified. Labeling of penicillamine di sulfide with 99mTc by direct reduction with SnCl2 did not give favorable good results while the 99mTc complex of penicillamine can be easily obtained. Ligand exchange reaction with 99mTc-gluconate was attempted and a 95% labeling efficiency was obtained. Radiopharmaceutical potential of 99mTc-PADS (99mTc-Penicillamine di sulfide) has been investigated with a gamma camera in rabbits and the complex was found to be uptaken mostly by the liver and kidneys.

Synthesis and iodine-125 labelling of glucuronide compounds for combined chemo- and radiotherapy of cancer.

Some types of cancer cells have high levels of beta-glucuronidase activity. This enzyme is able to deglucuronidate a variety of glucuronide derivatives on the cell membrane. Either O- or N-glucuronides can be selectively incorporated into the cancer cells. If the aglycone is cytotoxic, the glucuronide can potentially be used as a selective anti-cancer drug in cancers with high levels of beta-glucuronidase activity. Nevertheless, in vitro studies carried out by various investigators have shown that the cytotoxicities of several glucuronides in cancer cells are not sufficiently high for their use as effective anti-cancer drugs. For this reason, we have synthesized glucuronide compounds radiolabelled with iodine-125 combining the radiotoxicity of this Auger electron emitter with the chemotoxicity of the aglycone portion of the glucuronide.

Direct radioiodination of metabolic 8-hydroxy-quinolyl-glucuronide, as a potential anti-cancer drug.

8-Hydroxy-quinolyl-glucuronide (8-HOQ-Glu) can be deglucuronidated by the beta-glucoronidase enzyme, which has an activity that is considerably high in certain kinds of cancer cell. Owing to this enzyme activity, 8-HOQ-Glu can be considered as a potential anti-cancer drug. The combination of the radiotoxicity known of 125I nuclide with the cytotoxicity of 8-hydroxy-quinoline (8-HOQ) and particularly the selective carrying of 125I into the cancer cells is the principal aim of this study. As a first step, the metabolic 8-HOQ-Glu was extracted from the urine of rabbits treated with 8-HOQ directly radioiodinated using the iodogen method. The results showed that the radioiodination was successfully realized, and its yield was found to be about 90-95%.

Synkavit and its direct labelling with iodine-125, as a potential anti-cancer drug.

The compound known as "synkavit" is a diphosphate derivative of vitamin K3 (menadion), which is capable of being selectively accumulated in certain tumour cells, and covalently bonded to DNA producing considerable DNA damage. On the other hand, iodine-125 nuclide incorporated into the nucleus of living cells causes extreme radiotoxic effects. Consequently, synkavit can be used as a specific carrier of iodine-125 into the nucleus of tumour cells. Thus, its iodo-derivatives have become interesting agents on the potential application of iodine-125 in cancer therapy. 6-Iodo-synkavit is a unique iodo-derivative described in the literature. In addition, its synthesis and radioiodination is still problematic, and consequently the results obtained using 6-iodo-synkavit labelled with iodine-125 remains in question. For this reason, the synthesis of 6-iodo-synkavit was examined in this study. It is finally determined that a mixture of different iodo-isomers of synkavit has been produced rather than its specific 6-iodo-isomer, when the synthetic sequence was begun with the direct sulfonation of 2-methyl-naphthalene. On the other hand, it is also determined that synkavit can directly be radioiodinated using different iodination techniques, and iodogen especially can be successfully used as an oxidative agent.

Microscopic energy absorption in the colloid of thyroid follicles from Auger electrons of iodine-125.

In this study the microscopic energy absorption from Auger electrons of iodine-125 in colloid of two different thyroid models, which represent the normal and thyrotoxic thyroid glands, was theoretically calculated. These calculations were based on the method recently given by Unak (1987; Nucl. Intrum. Meth. Phys. Res. A255, 274) and the Auger electron spectrum given by Charlton and Booz (1981; Radiat. Res. 87, 10). Subsequently the range of highest energy Auger electrons of iodine-125 in thyroidal colloid was found to be about 72 microns. This range is considerably shorter than the radius of a normal thyroid follicle, about 150 microns, but is considerably longer than the 25 microns radius of a thyrotoxic thyroid follicle. On the other hand, the comparison of dose distributions in two different thyroid models showed that the similar activity of iodine-125 per gram of thyroid tissue is able to produce more radiotoxic effects on the thyrotoxic follicular cells.

Microscopic energy absorption of the DNA molecules from Auger electrons of iodine-125.

The microscopic energy distribution along the DNA duplex due to local absorption of Auger electrons of iodine-125 incorporated into the DNA molecule, has been theoretically calculated. Our calculation method [Unak T. Nucl. Instrum. Methods A255, 274 (1987); Unak T Ibid. A255, 281 (1987)] recently presented for spatial energy distribution from low-energy electrons in different chemical systems, has also been used for these calculations. As a result, it has been determined that the maximum range of the highest energy 125I Auger electrons in a linear DNA duplex is about 38 micron, and the total energy absorbed by DNA molecule per decay is about 10.3 keV, which is approximately half of the total energy released by electrons (19.8 keV per decay). This absorbed energy is not uniformly distributed along the DNA duplex. Consequently, it has also been determined that the microscopic energy absorption per DNA base or sugar-phosphate group rapidly decreased with the distance from the 125I nuclide, and reached about 5 eV per DNA base or sugar-phosphate group at a distance of about 2 nm. On the other hand, the results also demonstrated that the local absorption of 125I Auger electrons is able to produce alone at least one double strand break (DSB) on the DNA duplex without the support of the neutralization effects of highly charged tellurium ions.