Abstract    Issue Title: Proceedings of the World Molecular Imaging Congress 2015, Honolulu, Hawaii, September 2-5, 2015

Abstract  Zn is essential for growth and development. The bioavailability of Zn is affected by several factors such as other food components. It is therefore of interest, to understand uptake mechanisms of Zn delivering compounds to identify ways to bypass the inhibitory effects of these factors. Here, we studied the effect of Zn amino acid conjugates (ZnAAs) on the bioavailabilty of Zn. We used Caco-2 cells and enterocytes differentiated from human induced pluripotent stem cells from a control and Acrodermatitis enteropathica (AE) patient, and performed fluorescence based assays, protein biochemistry and atomic absorption spectrometry to characterize cellular uptake and absorption of ZnAAs. The results show that ZnAAs are taken up by AA transporters, leading to an intracellular enrichment of Zn mostly uninhibited by Zn uptake antagonists. Enterocytes from AE patients were unable to gain significant Zn through exposure to ZnCl2 but did not show differences with respect to ZnAAs. We conclude that ZnAAs may possess an advantage over classical Zn supplements such as Zn salts, as they may be able to increase bioavailability of Zn, and may be more efficient in patients with AE.

Abstract  As the limits of existing treatments for cancer are recognized, clearly novel therapies must be considered for successful treatment; cancer therapy using adenovirus vectors is a promising strategy. However tracking the biodistribution of adenovirus vectors in vivo is limited to invasive procedures such as biopsies, which are error prone, non-quantitative, and do not give a full representation of the pharmacokinetics involved. Current non-invasive imaging strategies using reporter gene expression have been applied to analyze adenoviral vectors. The major drawback to approaches that tag viruses with reporter genes is that these systems require initial viral infection and subsequent cellular expression of a reporter gene to allow non-invasive imaging. As an alternative to conventional vector detection techniques, we developed a specific genetic labeling system whereby an adenoviral vector incorporates a fusion between capsid protein IX and human metallothionein. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional metallothionein (MT) as a component of their capsid surface. We demonstrate the feasibility of (99m)Tc binding in vitro to the pIX-MT fusion on the capsid of adenovirus virions using a simple transchelation reaction. SPECT imaging of a mouse after administration of a (99m)Tc-radiolabeled virus showed clear localization of radioactivity to the liver. This result strongly supports imaging using pIX-MT, visualizing the normal biodistribution of Ad primarily to the liver upon injection into mice. The ability we have developed to view real-time biodistribution in their physiological milieu represents a significant tool to study adenovirus biology in vivo.

Abstract  One novel styrylpyridine derivatives(AV-45) coupled with Tc-99m complex was synthesized. Tc-99m-BAT-AV-45 was prepared by a ligand exchange reaction employing sodium glucoheptonate, and effects of the amount of ligand, stannous chloride, sodium glucoheptonate and pH value of reaction mixture on the radiolabeling yield were studied in details. Quality control was performed by thin layer chromatography and high performance liquid chromatography. Besides the stability, partition coefficient and electrophoresis of Tc-99m-BAT-AV-45 were also investigated. The results showed that the average radiolabeling yield was (95 +/- 1%) and Tc-99m-BAT-AV-45 with suitable lipophilicity was stable and uncharged at physiological pH.

Abstract  The subject of these studies was the thyroid gland tissue of middle-aged (14-month-old) female rats chronically treated with calcium glucoheptonate. The peripheral and central zone of the thyroids were stereologically analysed and the following morphometric parameters determined: the height and volumetric density of follicular epithelium, colloid, interstitium and follicles and index of activation rate. The height of follicular epithelium, its volume density and index of activation rate were significantly reduced (by 8%, p < 0.05, 18%, p < 0.025 and 34%, p < 0.01, respectively) as compared to the controls. However, the volumetric density of colloid and interstitium were increased (by 10% and 14% respectively). These morphometric results indicate that Ca treatment expressed an inhibitory effect on thyroid follicular cells structure in middle-aged female rats.

Abstract  The synthesis and labeling of (99m)Tc-N(3)-{N'-[2-sulfanyl-ethylamino)acetyl]-2-aminoethyl-sulfanyl-1-hexanamide]thymidine ((99m)Tc-NHT) were studied. In the presence of sodium glucoheptonate (GH) and ethylene diamine tetraacetic acid (EDTA), (99m)Tc-NHT was obtained by using bisaminoethanethiol (N(2)S(2)) as a bifunctional coupling agent. The radiochemical purity of the (99m)Tc-NHT was over 95%. Biodistribution of (99m)Tc-NHT was performed in hepatoma HepA tumor-bearing mice. At 2 h p.i., the ratios of tumor-to-muscle, tumor-to-bone and tumor-to-blood were 4.41 +/- 0.32, 2.45 +/- 0.24 and 1.51 +/- 0.18, respectively. (C) 2011 Chun Xiong Lu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Abstract  Radiopharmaceuticals are employed in patient diagnostics and disease treatments. Concerning the diagnosis aspect, technetium-99m (99mTc) is utilized to label radiopharmaceuticals for single photon computed emission tomography (SPECT) due to its physical and chemical characteristics. 99mTc fixation on pharmaceuticals depends on a reducing agent, stannous chloride (SnCl(2)) being the most widely-utilized. The genotoxic, clastogenic and anegenic properties of the 99mTc-MDP(methylene diphosphonate used for bone SPECT) and SnCl(2) were evaluated in Wistar rat blood cells using the Comet assay and micronucleus test. The experimental approach was to endovenously administer NaCl 0.9% (negative control), cyclophosphamide 50 mg/kg b.w. (positive control), SnCl(2) 500 &#956;g/mL or 99mTc-MDP to animals and blood samples taken immediately before the injection, 3, and 24 h after (in the Comet assay) and 36 h after, for micronucleus test. The data showed that both SnCl(2) and 99mTc-MDP-induced deoxyribonucleic acid (DNA) strand breaks in rat total blood cells, suggesting genotoxic potential. The 99mTc-MDP was not able to induce a significant DNA strand breaks increase in in vivo assays. Taken together, the data presented here points to the formation of a complex between SnCl(2) in the radiopharmaceutical 99mTc-MDP, responsible for the decrease in cell damage, compared to both isolated chemical agents. These findings are important for the practice of nuclear medicine.

Abstract  The compatibility of dopamine hydrochloride (Intropin) with various additives in 5% Dextrose Injection, USP, was studied. Dopamine hydrochloride stability for 24 hours in the admixture was established by colorimetric and thin-layer chromatographic procedures. Dopamine hydrochloride solutions are generally stable at an acidic pH and all admixtures produced a slightly acidic solution. Additives tested and found stable for 24 hours in the presence of Intropin included heparin sodium, lidocaine hydrochloride, neutral cephalothin sodium, oxacillin sodium and gentamicin sulfate. The chemical stability of methylprednisolone sodium succinate and hydrocortisone sodium succinate was not established. Potassium chloride, calcium chloride and calcium gluceptate may be assumed to be stable in the presence of Intropin. Above pH 5.0, the calcium gluceptate-Intropin admixture exhibited a color change indicating physical incompatibility. The pH and physical compatibility of all admixtures were established. In order to avoid a fixed combination of potent drugs, it is recommended that a "piggyback" administration set or administration into a second injection site be employed when another drug is to be administered with Intropin.

Abstract  The pituitary TSH cell structure of middle-aged (14-month-old) female Wistar rats chronically treated with estradiol dipropionate (EDP), calcium glucoheptonate (Ca) or with the combination of both was studied. TSH-producing cells were examined in the pituitary pars distalis using rabbit anti-rat beta-thyrotropin (TSH) serum and peroxidase-antiperoxidase immunohistochemistry. A stereological method for the determination of morphometric changes of the volume of TSH cells and nuclei as well as of their number and relative volume densities was used. All examined morphometric parameters in treated animals showed a significant decrease in comparison with immunoreactive TSH cells of the controls; the most significant decrease was observed in EDP-treated rats. These results together with structural features of immunoreactive TSH cells in the pituitary of middle-aged rats after chronic application of EDP or Ca indicate that both compounds inhibit these cells.

Abstract  Solutions of glucoheptonate and sodium pertechnetate (Tc-99m) were subjected to electrolysis at various ampere-time products until a charge was found that consistently promoted tagging of greater than 90% efficiency. It was found that 9 coulombs (100 mA, 90 sec) consistently yielded a final product that contained less than 10% total radiochemical impurities (unbound pertechnetate and reduced, hydrolyzed technetium). Radiochemical purity of the final product was established using a two-solvent thin-layer chromatographic system with methyl-ethyl ketone and normal saline as the solvents. The tagging efficiency and stability of the tagged complex were determined with similar chromatographic analysis. It was shown that use of a 15% solution of calcium glucoheptonate resulted in a more stable product than that prepared from commercially available stannous glucoheptonate. The rapid, accurate chromatographic method for determination or radiochemical purity of the product is described. The final product is considered equal or superior to commercial Tc-99m (Sn) glucoheptonate and was produced at considerably less cost.

Abstract  The effect of calcitonin on pancreatic secretion was studied in unanesthetized dogs with a Thomas cannula implanted opposite the main pancreatic duct. Pancreatic juice was collected for a 60 minute control period, during which time secretion was stimulated by the intravenous infusion of secretin and pancreozymin. After the 60 minute control period, calcitonin was infused along with the secretin and pancreozymin. The infusion of calcitonin caused the volume, bicarbonate and enzyme output in the pancreatic juice to decrease to about one-half of that during the control period. During the one hour period, after calcitonin infusion was stopped, the volume, bicarbonate and enzyme content of the pancreatic juice increased but remained slightly lower than that of the control period. The infusion of calcium gluceptate, along with secretin and pancreozymin, overcame the inhibitory effect of calcitonin on pancreatic secretion.

Abstract  Monoclonal antibodies can be labelled with technetium-99m by prereduction of the antibody with 2-mercaptoethanol, then reduction of pertechnetate with an aliquot of a stannous kit, resulting in greater than 97% labelling without the need for further purification. The present work shows that equally high labelling can be obtained with a variety of weak ligands and that the optimum quantity of stannous chloride is 2-4 micrograms. Although the label was stable to challenge with excess DTPA, cysteine was able to remove a portion of the label. We have also shown that this technique works with the IgG2a isotype in addition to the previously reported IgG1 isotype. This approach is simple, convenient and reproducible, and warrants further clinical evaluation.

Abstract  Methods for labeling antibodies with 99mTc cannot be used without modification for radiorhenium despite the similar chemistries, in part because of a lower redox potential of rhenium and therefore a greater tendency to reoxidize. We have investigated conditions for directly labeling B72.3 IgG with 188Re via both mercaptoethanol and stannous ion antibody reduction. The reduced 188Re was stabilized for transchelation as the glucoheptonate complex and transchelated in the presence of excess stannous ion. End points were low "non-specific" binding (i.e. labeling in the absence of antibody reduction) and increased stability to cysteine challenge. By both methods, labeling efficiencies after about 15 minutes averaged 58.77% with as little as 4% non-specific binding. Specific activities of 15 muCi/microgram was achieved after 1.5 hours. By investigating labeling condition, it was possible to improve the stability of the label on stannous ion reduced antibody such that the in vitro and in vivo properties of 188Re were largely independent of labeling method. For example, losses of 188Re due to oxidation (16%) and to cysteine (7%) during 37 degrees C serum incubations for 24 hours were identical for both methods. Furthermore, after the administration to normal mice, whole body clearance and the accumulations of 188Re at 2.5 and 24 hours in blood and in most organs were also independent of labeling method. In conclusion, two different direct labeling methods provided a 188Re-labeled antibody with identical stabilities and with in vivo properties not greatly different from that seen for the same antibody radiolabeled directly with 99mTc.

Abstract  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.

Abstract  Gelchromatography column scanning has been used to study the fractions of reduced hydrolyzed 99mTc, 99mTc-pertechnetate and 99mTc-chelate in a 99mTc-glucoheptonate (GH) preparation. A stable high labelling yield of 99mTc-GH complex in the radiopharmaceutical has been obtained with a concentration of 40-50 mg of glucoheptonic acid-calcium salt and not less than 0.45 mg of SnCl2.2 H2O at an optimal pH between 6.5 and 7.0. The stability of the complex has been found significantly affected when sodium hydroxide solution was used for the pH adjustment. However, an alternative procedure for final pH adjustment of the preparation has been investigated providing a stable complex for the usual period of time prior to the injection. The organ distribution and the blood clearance data of 99mTc-GH in rabbits were relatively similar to those reported earlier. The mean concentration of the radiopharmaceutical in both kidneys has been studied in normal subjects for one hour with a scintillation camera and the results were satisfactory.

Abstract  INTRODUCTION: Achieving an ideal (99m)Tc labeled nitroimidazole hypoxia marker is still considered to be of great interest. Metronidazole xanthate (MNXT) ligand was synthesized and radiolabeled with (99m)Tc-glucoheptonate (GH) to form the (99m)TcO-MNXT complex, for the potential use as a novel probe for imaging tumor hypoxia.

METHODS: For labeling, (99m)TcO-MNXT was prepared by ligand-exchange reaction with (99m)Tc-GH. The radiochemical purity of the (99m)TcO-MNXT complex was measured by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The distribution coefficient and stability of the complex was investigated. The structure of the (99m)TcO-MNXT complex was verified by preparation and characterization of the corresponding stable rhenium complex. The cellular uptake of the (99m)TcO-MNXT complex was determined in murine sarcoma S180 cell lines under hypoxic and aerobic conditions. The biodistribution and single photon emission computed tomography (SPECT) image studies of the (99m)TcO-MNXT complex were performed in mice bearing S 180 tumor.

RESULTS: The radiochemical purity of the (99m)TcO-MNXT complex was over 90%. It had good in vitro stability and its distribution coefficient indicated that it was a hydrophilic complex. When (99m)Tc and Re complexes were coinjected in HPLC, both radioactivity (for (99m)Tc complex) and UV detectors (for Re complex) showed nearly identical HPLC profiles, suggesting their structures are similar. The tumor cell experiment and the biodistribution in mice bearing S 180 tumor showed that the (99m)TcO-MNXT complex had a good hypoxic selectivity and accumulated in the tumor with high uptake and good retention. Single photon emission computed tomography (SPECT) image studies showed that the tumor detection was observable.

CONCLUSIONS: (99m)TcO-MNXT is prepared from a kit without the need for purification and shows high tumor uptake, tumor/blood and tumor/muscle ratios, suggesting that it would be a promising candidate for imaging tumor hypoxia.

Abstract  A new method, based on the pretreatment of leukocytes with glucoheptonate prior to treating with reduced 99mTc, has been developed for the preparation of 99mTc labelled leukocytes. The leukocytes labelled with a 99mTc concentration (5.59%/g tissue) similar to that of 111In-leukocytes (6.27%/g tissue), in the experimental abscess were in rat thigh. Concentration of 99mTc-leukocytes in blood at 24 h was only about 35% as compared to that of 111In-leukocytes. Biodistribution in the rat organs was similar in both cases, except in the liver where 99mTc-leukocytes exhibited about 4-fold greater concentration. Images of experimental abscess in rat by using 99mTc-leukocytes were comparable to those obtained with 111In-leukocytes.

Abstract  INTRODUCTION: The purpose of this study was to examine whether (99m)Tc-labeled Arg-Gly-Asp (RGD)-conjugated alpha-melanocyte stimulating hormone (α-MSH) hybrid peptide targeting both melanocortin-1 (MC1) and α(v)β(3) integrin receptors was superior in melanoma targeting to (99m)Tc-labeled α-MSH or RGD peptide targeting only the MC1 or α(v)β(3) integrin receptor.

METHODS: RGD-Lys-(Arg(11))CCMSH, RAD-Lys-(Arg(11))CCMSH and RGD-Lys-(Arg(11))CCMSHscramble were designed to target both MC1 and α(v)β(3) integrin receptors, MC1 receptor only and α(v)β(3) integrin receptor only, respectively. The MC1 or α(v)β(3) integrin receptor binding affinities of three peptides were determined in M21 human melanoma cells. The melanoma targeting properties of (99m)Tc-labeled RGD-Lys-(Arg(11))CCMSH, RAD-Lys-(Arg(11))CCMSH and RGD-Lys-(Arg(11))CCMSHscramble were determined in M21 human melanoma-xenografted nude mice. Meanwhile, the melanoma uptake of (99m)Tc-RGD-Lys-(Arg(11))CCMSH was blocked with various non-radiolabeled peptides in M21 melanoma xenografts.

RESULTS: RGD-Lys-(Arg(11))CCMSH displayed 2.0 and 403 nM binding affinities to both MC1 and α(v)β(3) integrin receptors, whereas RAD-Lys-(Arg(11))CCMSH or RGD-Lys-(Arg(11))CCMSHscramble lost their α(v)β(3) integrin receptor binding affinity by greater than 248-fold or MC1 receptor binding affinity by more than 100-fold, respectively. The melanoma uptake of (99m)Tc-RGD-Lys-(Arg(11))CCMSH was 2.49 and 2.24 times (P < .05) the melanoma uptakes of (99m)Tc-RAD-Lys-(Arg(11))CCMSH and (99m)Tc-RGD-Lys-(Arg(11))CCMSHscramble at 2 h post-injection, respectively. Either RGD or (Arg(11))CCMSH peptide co-injection could block 42% and 57% of the tumor uptake of (99m)Tc-RGD-Lys-(Arg(11))CCMSH, whereas the coinjection of RGD+(Arg(11))CCMSH peptide mixture could block 66% of the tumor uptake of (99m)Tc-RGD-Lys-(Arg(11))CCMSH.

CONCLUSIONS: Targeting both MC1 and α(v)β(3) integrin receptors enhanced the melanoma uptake of (99m)Tc-RGD-Lys-(Arg(11))CCMSH in M21 human melanoma xenografts. Flank M21 human melanoma tumors were clearly visualized by single photon emission computed tomography/computed tomographic imaging using (99m)Tc-RGD-Lys-(Arg(11))CCMSH as an imaging probe, highlighting its potential use as a dual-receptor-targeting imaging probe for human melanoma detection.