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Manganese is a paramagnetic element suitable for magnetic resonance imaging (MRI) of neuronal function. However, high concentrations of MnThis work focuses on the development of precise simulations and models to compare theThe nuclear code Talys has been employed to optimize theGood agreement was obtained between cross-section calculations and measurements. The comparison of the two reaction channels suggests thatBoth

This research aimed to prepare 99mTc-/177Lu-CXCR4-L radiotracers and evaluate their in vitro and in vivo capability to detect the chemokine-4 receptor. Molecular docking calculations, Kd values ( 98.5%) estimated by saturation binding assays, as well as biodistribution studies in mice with induced tumors, confirmed the affinity of radiotracers towards CXCR4, expressed in DU-4475 breast cancer cells and C6 glioblastoma cells. Micro-SPECT/CT images showed that 99mTc-CXCR4-L and 177Lu-CXCR4-L could work as a theranostic pair for CXCR4 targets. Results warrant additional research to assess the therapeutic efficacy and dosimetry of 177Lu-CXCR4-L.

Fibroblast activation protein (FAP) is expressed in the microenvironment of most human epithelial tumors. 68Ga-labeled FAP inhibitors based on the cyanopyrrolidine structure (FAPI) are currently used for the detection of the tumor microenvironment by PET imaging. This research aimed to design, synthesize and preclinically evaluate a new FAP inhibitor radiopharmaceutical based on the 99mTc-((R)-1-((6-hydrazinylnicotinoyl)-D-alanyl) pyrrolidin-2-yl) boronic acid (99mTc-iFAP) structure for SPECT imaging. Molecular docking for affinity calculations was performed using the AutoDock software. The chemical synthesis was based on a series of coupling reactions of 6-hidrazinylnicotinic acid (HYNIC) and D-alanine to a boronic acid derivative. The iFAP was prepared as a lyophilized formulation based on EDDA/SnCl2 for labeling with 99mTc. The radiochemical purity (R.P.) was verified via ITLC-SG and reversed-phase radio-HPLC. The stability in human serum was evaluated by size-exclusion HPLC. In vitro cell uptake was assessed using N30 stromal endometrial cells (FAP positive) and human fibroblasts (FAP negative). Biodistribution and tumor uptake were determined in Hep-G2 tumor-bearing nude mice, from which images were acquired using a micro-SPECT/CT. The iFAP ligand (Ki = 0.536 nm, AutoDock affinity), characterized by UV-Vis, FT-IR, 1H–NMR and UPLC-mass spectroscopies, was synthesized with a chemical purity of 92%. The 99mTc-iFAP was obtained with a R.P. >98%. In vitro and in vivo studies indicated high radiotracer stability in human serum (>95% at 24 h), specific recognition for FAP, high tumor uptake (7.05 ± 1.13% ID/g at 30 min) and fast kidney elimination. The results found in this research justify additional dosimetric and clinical studies to establish the sensitivity and specificity of the 99mTc-iFAP.

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticle solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions’ temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation.

Purpose Technetium-99m (99m Tc) is the radioisotope most widely used in diagnostic nuclear medicine. It is readily available from 99 Mo/99m Tc generators as the β- decay product of the 99 Mo (Tf = 66 h) parent nuclide. This latter is obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct reactions using proton beams on specific target materials [100 Mo(p,2n)99m Tc], have the potential to be both reliable and relatively cost-effective. However, results showed that the 99m Tc extracted from proton-bombarded 100 Mo-enriched targets contains small quantities of several Tc radioisotopes (93m Tc, 93 Tc, 94 Tc, 94m Tc, 95 Tc, 95m Tc, 96 Tc, and 97m Tc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotron-produced 99m Tc (CP-99m Tc) using 99.05% 100 Mo-enriched metallic targets. Methods Four 99m Tc radiopharmaceuticals (pertechnetate, sestamibi (MIBI), hexamethylpropylene-amine oxime (HMPAO) and disodium etidronate (HEDP)) were considered in this study. The biokinetic models reported by the International Commission on Radiological Protection (ICRP) for each radiopharmaceutical were used to define the main source organs and to calculate the number of disintegrations per MBq that occurred in each source organ (Nsource ) for each Tc radioisotope present in the CP-99m Tc solution. Then, target organ equivalent doses and effective dose were calculated for each Tc radioisotope with the OLINDA/EXM software versions 1.1 and 2.0, using the calculated Nsource values and the adult male phantom as program inputs. Total effective dose produced by all Tc isotopes impurities present in the CP-99m Tc solution was calculated using the fraction of total activity corresponding to each radioisotope and compared with the effective dose delivered by the generator-produced 99m Tc. Results In all cases, the total effective DI of CP-99m Tc radiopharmaceuticals calculated with either versions of the OLINDA software was less than 10% from 6 up to 12 h after EOB. 94m Tc and 93m Tc are the Tc radioisotopes with the highest concentration in the CP-99m Tc solution at EOB. However, their contribution to DI 6 h after EOB is minimal, due to their short half-lives. The radioisotopes with the largest contribution to the effective DI are 96 Tc, followed by 95 Tc and 94 Tc. This is due to the types of their emissions and relatively long half-lives, although their concentration in the CP-99m Tc solution is five times lower than that of 94m Tc and 93m Tc at the EOB. Conclusions The increase in the radiation dose caused by other Tc radioisotopes contained in CP-99m Tc produced as described here is quite low. Even though the concentrations of the 94 Tc and 95 Tc radioisotopes in the CP-99m Tc solution exceed the limits established by the European Pharmacopoeia, CP-99m Tc radiopharmaceuticals could be used in routine nuclear medicine diagnostic studies if administered from 6 to 12 h after the EOB, thus maintaining the effective DI within the 10% limit.

Internal dosimetry has become a very important tool to evaluate the risks and benefits of new endoradiotherapeutic agents. Nowadays, some of the most successful targeted radionuclide therapy (TRT) agents areAllIn this preclinical study, we demonstrated the potential of

Purpose Internal dosimetry has become a very important tool to evaluate the risks and benefits of new endoradiotherapeutic agents. Nowadays, some of the most successful targeted radionuclide therapy (TRT) agents are 177 Lu-DOTA conjugates based on low molecular weight (LMW) Glu-ureido PSMA inhibitors. It has however been demonstrated that the DOTA chelating moiety reduces the internalization of the LMW-PSMA agent and its radiation dose to the tumour. Previously, we reported that 177 Lu-scFvD2B, an antibody-based construct, demonstrated statistically significant higher cell uptake and internalization in LNCaP prostate cancer (PCa) cells (PSMA-positive) when compared to the LMW-PSMA agents 177 Lu-PSMA-617 and 177 Lu-iPSMA, two of the endoradiotherapeutic agents which currently are the most used in PCa therapy. The aim of this study is to estimate the preclinical 177 Lu-scFvD2B organ and tumor-absorbed doses and to compare the values with those of 177 Lu-PSMA-617 and 177 Lu-iPSMA. Methods 177 Lu-scFvD2B, 177 Lu-PSMA-617 and 177 Lu-iPSMA were prepared and their radiochemical purity determined. Biodistribution studies of each radiopharmaceutical were then carried out in healthy mice to define the main source organs (SO) and to calculate the number of disintegrations in each source organs per unit of administered activity (NSO ). Absorbed dose in the main organs were then calculated for each 177 Lu-conjugate by means of OLINDA/EXM 2.1.1 software, using the calculated NSO for both the adult male and the mouse phantoms as program inputs. Images of mice bearing micro-pulmonary tumors injected with 177 Lu-conjugates were also obtained. Tumor standardized uptake values (SUV) for the different conjugates, obtained from the 3D SPECT image reconstruction of these mice, were used as the number of disintegrations in a tumor site per unit of administered activity (NT ). The tumor-absorbed dose was calculated using the published electron dose S-values for sphere models with diameters ranging from 10 µm to 10 mm and considering a uniform activity distribution and tumor density equivalent to water density. Results All 177 Lu-labelled agents were obtained in high yield (98%). Dosimetric studies carried out using mouse phantoms demonstrated that organ absorbed doses of 177 Lu-scFvD2B were from 1.4 to 2.3 times higher than those for 177 Lu-iPSMA and from 1.5 to 2.6 times higher than those for 177 Lu-PSMA-617. However, the 177 Lu-scFvD2B values of tumor-absorbed doses for all investigated tumor sizes were from 2.8 to 3.0 times greater than those calculated for 177 Lu-iPSMA and 177 Lu-PSMA-617, respectively. Moreover, 177 Lu-scFvD2B showed the highest tumor/kidney ratio when compared to those reported for 177 Lu-albumin conjugates. Conclusions In this preclinical study, we demonstrated the potential of 177 Lu-scFvD2B as a therapeutic agent for PSMA-expressing tumors, due to its higher tumor-absorbed dose when compared with 177 Lu-LMW agents.

Polymeric nanoparticles encompass micelles and dendrimers. They are used for improving or controlling the action of the loaded therapy or imaging agent, including radionuclides. Some radionuclides possess properties appropriate for simultaneous imaging and therapy of a disease and are therefore called theranostic. The diversity in core materials and surface modification, as well as radiolabeling strategies, offers multiples possibilities for preparing polymeric nanoparticles using radionuclides. The present review describes different strategies in the preparation of such nanoparticles and their applications in nuclear nanomedicine.

[Tc-99m][TcN-DBODC(5) is the lead candidate of a class of cationic complexes proposed as myocardial imaging agents (MPIAs). Phase I clinical studies showed that its clinical properties were comparable to those of the commercially available agents. Thus, modification of [Tc-99m]TcN-DBODC(5), directed to obtain an ideal myocardial imaging without interference from the adjacent organ activities, is desirable. This work describes the pharmacological and pharmacokinetic development of four new complexes of general formula [Tc-99m][Tc(N)(DASD)(PNPn)](+), [Tc-99m]TcN-DASD(n) (DASD = 1,4-dioxa-8-azaspiro[4,5]decandithiocarbamate; PNPn = bisphosphinoamine), proposed as improved MPIAs. Among the tested compounds, [Tc-99m]TcN-DASD(5) and [Tc-99m]TcN-DASD(7) showed enhanced heart uptake compared with the gold standards, with a rapid liver washout and superior heart-to-liver ratio. These features might shorten the duration of imaging procedures below 30 min, consenting the early acquisition of high-quality images. In addition, mechanistic studies were performed in cellulo by using human drug-sensitive and drug-resistant cancer cell lines, obtaining results which might be conveniently applied to tumor imaging.

Gamma-ray spectrometry analyses of the radionuclide content of eluate from two Mo-99/Tc-99m radionuclide generators POLTECHNET have been performed. The relative activities of 99Mo 103Ru and 131I radioisotopes with respect to the activity of 99mTc at different time intervals after the primary pertechnetate elution of the generators have been analyzed. The relative activities of the isotopes were determined and compared to the radionuclidic purity requirements for 99mTc.

Medicinal plants produce various secondary metabolites as a part of their chemical defence and survival in nature. These compounds have a wide range of biological activities. Nowadays, medicinal plants are used as source of allelochemicals and new effective anticancer agents. Our previous studies revealed allelopathic potential of water extracts of Adonis vernalis L. (Ranunculaceae), Origanum vulgare ssp. vulgare L. and Nepeta nuda subsp. nuda (Lamiaceae). Present study aimed to evaluate the effect of the same extracts in vitro on human hepatoma cell line SK-HEP-1. Cell proliferation/viability was assessed using Premixed WST-1 Cell Proliferation Reagent. Adonis water extract (1.83mg/ml) had notable negative influence on cancer cell line tested. Oregano (3.5 mg/ml) also exerted negative effect, but to a lesser degree. On the contrary, nepeta water extract (6.59 mg/ml) had an opposite effect, stimulating cell proliferation. One possible explanation could be the type of extraction: after treatment with nepeta methanol extract (6.59 mg/ml) cell viability was significantly reduced. In conclusion, Adonis vernalis and Nepeta nuda subsp. nuda possess metabolites with growth inhibitory effect on human hepatoma cell line SK-HEP-1. Further research is needed to clarify biological activity of lower concentrations which are appropriate to enable the design of new anticancer drugs.

Protein interactions are the basis for the biological functioning of human beings. However, many of these interactions are also responsible for diseases, including cancer. Synthetic inhibitors of protein interactions based on small molecules are widely investigated in medicinal chemistry. The development of radiolabeled protein-inhibitor peptides for molecular imaging and targeted therapy with quickstep towards clinical translation is an interesting and active research field in the radiopharmaceutical sciences. In this article, recent achievements concerning the design, translational research and theranostic applications of structurally-modified small radiopeptides, such as prostate-specific membrane antigen (PSMA) inhibitors, fibroblast activation protein (FAP) inhibitors and antagonists of chemokine-4 receptor ligands (CXCR-4-L), with high affinity for cancer-associated target proteins, are reviewed and discussed.

In order to establish the potential of [51/52Mn]Cl2 as safe PET brain tracers, the radiation effective dose (ED) of [51Mn]- and [52Mn]-chloride has been assessed by using biokinetic models in anthropomorphic phantoms. Results showed that [52Mn]-chloride releases one hundred thirty times more radiation dose (ED = 1.35 mSv/MBq) than [51Mn]-chloride (ED = 1.02E-02 mSv/MBq). Although the maximum positron energy of 52Mn allows a PET image resolution similar to that of 18F, activities below 15 MBq should be administered.

47Sc is one of the most promising theranostic radionuclides, thanks to its low energy γ-ray emission (159 keV), suitable for single photon emission computed tomography imaging and its intense β − emission, useful for tumour treatment. Despite promising preclinical results, the translation of 47Sc-therapeutic agents to the clinic is hampered by its limited availability. Among different 47Sc-production routes currently being investigated, the natV(p,x)47Sc reaction has proved to be of particular interest, thanks to the low-cost and easy availability on the market of natV material and the diffusion of medium energy proton cyclotrons. However, the cross section of this specific nuclear reaction is quite low and small amounts of Sc-contaminants are co-produced at energies E P ≤ 45 MeV, namely 48Sc and 46Sc. The main concern with these Sc-contaminants is their contribution to the patient absorbed dose. For such a reason, the absorbed dose contributions to healthy organs and the effective dose contributions by the three radioisotopes, 48Sc, 47Sc and 46Sc, were evaluated using DOTA-folate conjugate (cm10) as an example of radiopharmaceutical product. Considering as acceptable the limits of 99% for the radionuclidic purity and 10% for the contribution of radioactive Sc-contaminants to the total effective dose after 47Sc-cm10 injection, it was obtained that proton beam energies below 35 MeV must be used to produce 47Sc through irradiation of a natV target.

Radiolabeled targeted nanoparticles have been extensively studied for medical applications. Their multifunctionality and multivalency (among other properties) make them suitable candidates to target different diseases by means of pharmacophore groups for molecular, cellular, and/or tissue targeting. They have been used for molecular imaging and as drug delivery systems to improve drug efficacy and decrease side effects by passive accumulation of drugs in healthy tissues. Metallic nanoparticles can be radiolabeled or be radioactive themselves in order to deposit a large amount of energy into malignant cells, which produces irreversible damage. Because of their high surface area, these can be functionalized with small molecules and biomacromolecules for targeted radiotherapy. Moreover, their quantum size effect and resulting properties recently proved to produce hyperthermia. Polymeric nanoparticles are also acquiring importance in molecular imaging as diagnostic and therapeutic agents, due to their biocompatibility, biodegradability, and pharmacokinetic advantages, including the ability for controlled drug release or targeted radiotherapy. Both metallic and polymeric nanoparticles have been proposed as new, smart, pharmaceutical devices to produce dual-targeted therapy and molecular imaging. In this chapter, we will discuss the development and potential medical applications of radiolabeled metallic and polymeric nanoparticles as intelligent targeted systems.

Technetium-99m (FourIn all cases, the total effective DI of CP-The increase in the radiation dose caused by other Tc radioisotopes contained in CP

In the last years, the technology for producing the important medical radionuclide technetium-99m by cyclotrons has become sufficiently mature to justify its introduction as an alternative source of the starting precursor [99mTc][TcO4]- ubiquitously employed for the production of 99mTc-radiopharmaceuticals in hospitals. These technologies make use almost exclusively of the nuclear reaction 100Mo(p,2n)99mTc that allows direct production of Tc-99m. In this study, it is conjectured that this alternative production route will not replace the current supply chain based on the distribution of 99Mo/99mTc generators, but could become a convenient emergency source of Tc-99m only for in-house hospitals equipped with a conventional, low-energy, medical cyclotron. On this ground, an outline of the essential steps that should be implemented for setting up a hospital radiopharmacy aimed at the occasional production of Tc-99m by a small cyclotron is discussed. These include (1) target production, (2) irradiation conditions, (3) separation/purification procedures, (4) terminal sterilization, (5) quality control, and (6) Mo-100 recovery. To address these issues, a comprehensive technology for cyclotron-production of Tc-99m, developed at the Legnaro National Laboratories of the Italian National Institute of Nuclear Physics (LNL-INFN), will be used as a reference example.

About 90% of insulinomas are benign and 5%-15% are malignant. Benign insulinomas express the glucagon-like peptide-1 receptor (GLP-1R) and low levels of somatostatin receptors (SSTR), while malignant insulinomas over-express SSTR or GLP-1R in low levels. A kit for the preparation of Lys(27)((99m)Tc-EDDA/HYNIC)-Exendin(9-39)/(99m)Tc-EDDA/HYNIC-Tyr(3)Octreotide was formulated to detect 100% of insulinomas. The formulation showed radiochemical purity of 97±1%, high stability in human serum, and GLP-1R and SSTR affinity. The biodistribution and imaging studies demonstrated properties suitable for its use as a target-specific agent for the simultaneous molecular imaging of GRP-1R- and/or SSTR-positive tumors.

Gold nanoparticles (AuNPs) have been proposed for a variety of medical applications such as localized heat sources for cancer treatment and drug delivery systems. The conjugation of peptides to AuNPs produces stable multimeric systems with target-specific molecular recognition. Lutetium- 177 ( 177 Lu) has been successfully used in peptide radionuclide therapy. Recently, 177 Lu-AuNPs conjugated to different peptides have been proposed as a new class of theranostic radiopharmaceuticals. These radioconjugates may function simultaneously as molecular imaging agents, radiotherapy systems and thermal-ablation systems. This article covers advancements in the design, synthesis, physicochemical characterization, molecular recognition assessment and preclinical therapeutic efficacy of gold nanoparticles radiolabeled with 177 Lu and conjugated to RGD (-Arg-Gly-Asp-), Lys 3 -Bombesin and Tat(49-57) peptides.

A general procedure for the preparation of a new class of neutral six-coordinated mixed ligand [Tc-99m(III)(PS)(2)(Ln)] compounds (PS = trisalkyl-phosphino-thiolate; Ln = dithiocarbamate) is reported as well as their in vitro stability and the ex vivo tissue distribution studies. [Tc-99m(PS)(2)(Ln)] complexes were prepared in high yield in nearly physiologic conditions following a one-pot procedure. For instance, the chemical identity of [Tc-99m(PSiso)(2)(L1)] (PSiso = 2-(diisopropylphosphino)ethanethiol; L1 = pyrrolidine dithiocarbamate) was determined by HPLC comparison with the corresponding (99g)Tc-complex. All complexes comprise the stable [Tc-99m(III)(PS)(2)](+) moiety, where the remaining two coordination positions are saturated by a dithiocarbamate chelate, also carrying bioactive molecules (e.g., 2-methoxyphenylpiperazine). [Tc-99m(PS)(2)(Ln)] complexes were inert toward ligand exchange reactions. No significant in vitro and in vivo biotransformation were observed, underlining their remarkable thermodynamic stability and kinetic inertness. These results could be conveniently utilized to devise a novel class of Tc-99m(III)-based compounds useful in radiopharmaceutical applications.

The study was aimed at evaluating apoptotic potential of Br-oxph (4-bromoN,N-diethyl-5,5-dimethyl-2,5-dihydro-1,2-oxaphosphol-2-amine 2-oxide) in vitro. The dose response effect of Br-oxph (dose range 1-3 mg/ml, for 48 h) on SK-MES-1 cells viability was determined by means of WST-1 cell proliferation assay. The half maximal inhibitory concentration (??50) value was determined - 1.8 mg/ml. The ability of the compound tested to induce apoptosis was tested by ELISA to detect cellular DNA fragmentation. We provided a quantitative assessment of the apoptotic potential of Br-oxph in human lung carcinoma cells at concentrations corresponding to ??50 and 2???50 for 3 hours. Treatment with 2???50 significantly increased the amount of cytoplasmic DNA-fragments. Results obtained from the present study confirm that Br-oxph target the cancerous cells towards apoptosis.

The gastrin-releasing peptide receptor (GRPr) is overexpressed in >75% of breast cancers. 177Lu-Bombesin (177Lu-BN) has demonstrated the ability to target GRPr and facilitate efficient delivery of therapeutic radiation doses to malignant cells. Poly( d , l ‑lactide‑co‑glycolide) acid (PLGA) nanoparticles can work as smart drug controlled-release systems activated through pH changes. Considering that paclitaxel (PTX) is a first-line drug for cancer treatment, this work aimed to synthesize and chemically characterize a novel polymeric PTX-loaded nanosystem with grafted 177Lu-BN and to evaluate its performance as a targeted controlled-release nanomedicine for concomitant radiotherapy and chemotherapy of breast cancer. PLGA(PTX) nanoparticles were synthesized using the single emulsification-solvent evaporation method with PVA as a stabilizer in the presence of PTX. Thereafter, the activation of PLGA carboxylic groups for BN attachment through the Lys1-amine group was performed. Results of the chemical characterization by FT-IR, DLS, HPLC and SEM/TEM demonstrated the successful synthesis of BN-PLGA(PTX) with a hydrodynamic diameter of 163.54 ± 33.25 nm. The entrapment efficiency of paclitaxel was 92.8 ± 3.6%. The nanosystem showed an adequate controlled release of the anticancer drug, which increased significantly due to the pH change from neutral (pH = 7.4) to acidic conditions (pH = 5.3). After labeling with 177Lu and purification by ultrafiltration, 177Lu-BN-PLGA(PTX) was obtained with a radiochemical purity of 99 ± 1%. In vitro and in vivo studies using MDA-MB-231 breast cancer cells (GRPr-positive) demonstrated a 177Lu-BN-PLGA(PTX) specific uptake and a significantly higher cytotoxic effect for the radiolabeled nanosystem than the unlabeled BN-PLGA(PTX) nanoparticles. Using a pulmonary micrometastasis MDA-MB-231 model, the added value of 177Lu-BN-PLGA(PTX) for tumor imaging was confirmed. The 177Lu-BN-PLGA(PTX) nanomedicine is suitable as a targeted paclitaxel delivery system with concomitant radiotherapeutic effect for the treatment of GRPr-positive breast cancer.

Evaluation of the radioisotopic purity of technetium-99m (99mTc) produced in GBq amounts by proton bombardment of enriched molibdenum-100 (100Mo) metallic targets at low proton energies (i.e. within 15-20 MeV) is conducted. This energy range was chosen since it is easily achievable by many conventional medical cyclotrons already available in the nuclear medicine departments of hospitals. The main motivation for such a study is in the framework of the research activities at the international level that have been conducted over the last few years to develop alternative production routes for the most widespread radioisotope used in medical imaging. The analysis of technetium isotopes and isomeric states (9xTc) present in the pertechnetate saline Na99mTcO4 solutions, obtained after the extraction/purification procedure, reveals radionuclidic purity levels basically in compliance with the limits recently issued by European Pharmacopoeia 9.3 (2018 Sodium pertechnetate (99mTc) injection 4801-3). Moreover, the impact of 9xTc contaminant nuclides on the final image quality is thoroughly evaluated, analyzing the emitted high-energy gamma rays and their influence on the image quality. The spatial resolution of images from cyclotron-produced 99mTc acquired with a mini-gamma camera was determined and compared with that obtained using technetium-99m solutions eluted from standard 99Mo/99mTc generators. The effect of the increased image background contribution due to Compton-scattered higher-energy gamma rays (E γ > 200 keV), which could cause image-contrast deterioration, was also studied. It is concluded that, due to the high radionuclidic purity of cyclotron-produced 99mTc using 100Mo(p,2n)99mTc reaction at a proton beam energy in the range 15.7-19.4 MeV, the resulting image properties are well comparable with those from the generator-eluted 99mTc.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods 188 Re-HA was prepared by a direct labelling method to produce a ReO(O-COO) 2 -type coordination complex. 188 Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice ( n =60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of 188 Re-HA was determined. Results A stable complex of 188 Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance ( T 1/2 α=21 min). Four hours after administration, 188 Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47±5.11% of the injected dose). The liver MTD in mice was ∼40 Gy after 7.4 MBq of 188 Re-HA injection. Conclusions 188 Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

The antimicrobial peptide ubiquicidin (UBI) directly labeled with technetium-99m ( 99m Tc) has recently been shown to be specifically taken up at sites of infection; however, its chemical structure is not well defined. To address this problem, the aim of the present study was to label UBI using poly(ethyleneglycol)– N -( N -(3-diphenylphosphinopropionyl)glycyl)- S -tritylcysteine ligand (PEG-PN 2 S) in order to compare its ability to detect infection sites with that of 99m Tc-UBI. Methods The PN 2 S-PEG-UBI conjugate was prepared and labeled with 99m Tc, and its radiochemical purity was subsequently assessed. The stability of the conjugate to cysteine challenge and dilution with both saline solution and phosphate buffer was determined and serum stability and protein binding were also assessed. In vivo studies were carried out in healthy mice to study the biodistribution of 99m Tc-PN 2 S-PEG-UBI and its precursor 99m Tc-PN 2 S-PEG and in infected mice to compare the uptakes of 99m Tc-UBI and 99m Tc-PN 2 S-PEG-UBI at the site of infection using scintigraphic imaging and ex vivo tissue counting. Results 99m Tc-PN 2 S-PEG-UBI was obtained with high radiochemical purity (98±1%) and high stability. The amphiphilic nature of the conjugate leads to a tendency to form micellar aggregates that explain the high protein binding values obtained. Biodistribution studies in mice showed low renal clearance followed by a predominant reticuloendothelial system clearance that limits its application in the abdominal area. Statistical analysis revealed no significant difference between 99m Tc-UBI and 99m Tc-PN 2 S-PEG-UBI uptake in infected mouse thigh, and the site of infection was clearly visualized using scintigraphic imaging. Conclusions 99m Tc-PN 2 S-PEG-UBI proved to be as effective as 99m Tc-UBI in detecting sites of infection; however, the well-defined chemical structure of 99m Tc-PN 2 S-PEG-UBI makes it a better candidate for clinical imaging of infection.

Paclitaxel, an anti-tumour drug, shows good results against breast and ovarian cancer. However, its therapeutic response is associated with toxic side-effects caused by the agent used to dissolve it. Recently paclitaxel was linked to the linear polysaccharide hyaluronic acid (HA), showing good solubility, stabilization, localization and a reduction of cytotoxic side-effects. To study potential therapeutic applications, HA-paclitaxel bioconjugate (ONCOFID-P) was labelled with 99mTc by the addition of 99mTc-pertechnetate, SnCl2 and sodium gluconate. The reaction mixture was incubated for 90 min at 65°C and purified by size exclusion chromatography. The obtained 99mTc-ONCOFID-P had 100% radiochemical purity and was stable in a phosphate buffer dilution 1:100 for 6 h at 37°C. 99mTc-ONCOFID-P bioavailability studies were carried out in healthy mice using four different administration pathways. The analysis showed that after intravenous administration more than 80% of the injected radiopharmaceutical was found in liver and spleen. Intraperitoneal, intravesical and oral administrations showed that all the 99mTc-ONCOFID-P remained at the administration site. These results demonstrate that ONCOFID-P administered intravenously could be used for liver metastasis therapy due to its high physiological and receptor-specific liver uptake, while intravesical, intraperitoneal and oral administration of ONCOFID-P could be used for local treatment of superficial cancers. Copyright © 2006 John Wiley & Sons, Ltd.

The ubiquicidin 29-41 fragment (UBI) is a cationic antimicrobial peptide. The aim of this study was to develop an instant kit formulation for the preparation of 99mTc-UBI 29-41 in high radiochemical yield and to evaluate its use as an infection imaging agent in humans. The components were selected to produce a direct 99mTc labeling, presumably to the amine groups of Lys and Arg7. 99mTc-UBI 29-41 obtained from the lyophilized kit showed radiochemical purity of >97% with an average target/non-target ratio of 2.3±0.6 in positive infection sites at 2 hours. Kits were stable at 4 °C for over 6 months.

Antimicrobial peptides have been proposed as new agents to distinguish between bacterial infections and sterile inflammatory processes. (99m)Tc-UBI labeled by a direct method has shown high in vitro and in vivo stability, specific uptake at the site of infection, rapid background clearance, minimal accumulation in non-target tissues and rapid detection of infection sites in mice. The aim of this study was to establish a (99m)Tc-UBI biokinetic model and evaluate its feasibility as an infection imaging agent in humans. Whole-body images from 6 children with suspected bone infection were acquired at 1, 30, 120, 240 min and 24 h after (99m)Tc-UBI administration. Regions of interest (ROIs) were drawn around source organs (heart, liver, kidneys and bladder) on each time frame. The same set of ROIs was used for all 6 scans and the cpm of each ROI were converted to activity using the conjugate view counting method. Counts were corrected by physical decay and by the background correction factor derived from preclinical phantom studies. The image sequence was used to extrapolate (99m)Tc-UBI time-activity curves in each organ and calculate the cumulated activity (A). Urine samples were used to obtain the cumulative percent of injected activity (% I.A.) versus time renal elimination. The absorbed dose in organs was evaluated according to the general equation described in the MIRD formalism. In addition, (67)Ga-citrate images were obtained from all the patients and used as a control. Biokinetic data showed a fast blood clearance with a mean residence time of 0.52 h. Approximately 85% of the injected activity was eliminated by renal clearance 24 h after (99m)Tc-UBI administration. Images showed minimal accumulation in non-target tissues with an average target/non-target ratio of 2.18 +/- 0.74 in positive lesions at 2 h. All infection positive(99m)Tc-UBI images were in agreement with those obtained with (67)Ga-citrate. The mean radiation absorbed dose calculated was 0.13 mGy/MBq for kidneys and the effective dose was 4.34 x 10(-3)mSv/MBq.

Technetium-99m labeled ubiquicidin peptide 29-41 ((99m)Tc-UBI) is a cationic human antimicrobial peptide fragment that has been shown to bind bacteria in vitro and accumulates at sites of infection in experimental animals. To help determine if (99m)Tc-UBI is bound to the bacterial cell envelope by a simple nonspecific electrostatic interaction, a comparative study of the in vitro binding of (99m)Tc-UBI and two different (99m)Tc labeled cationic peptides ((99m)Tc-Tat-1-Scr and (99m)Tc-Tat-2-Scr) to bacteria and to two tumor cell line (LS174T and ACHN) was performed. The in vivo specificity of (99m)Tc-UBI for infection in mice was also evaluated using dual labels in the same animal and comparing the target/non-target ratio for (67)Ga-citrate and (99m)Tc-UBI at sites of induced infection and sterile inflammation. Under conditions of this study, the in vitro binding of (99m)Tc-UBI, (99m)Tc-Tat-1-Scr and (99m)Tc-Tat-2-Scr to S. aureus was 35, 78 and 87% respectively. While the binding of (99m)Tc-Tat-1-Scr and (99m)Tc-Tat-2-Scr was 37 and 33% to colon tumor cells (LS174T) and 39 and 41% to renal tumor cells (ACHN) respectively, the binding of (99m)Tc-UBI to both cell types was much lower at less than 4%. In vivo studies revealed that there is a significant difference (p < 0.05) in the radioactive accumulation of (99m)Tc-UBI between the sites of infection and inflammation compared to (67)Ga-citrate. Thus, (99m)Tc-UBI showed an average infection/inflammation ratio of 2.08 +/- 0.49 compared to 1.14 +/- 0.45 for (67)Ga-citrate. In conclusion, the in vitro and in vivo results provide evidence that a specific mechanism is responsible of the (99m)Tc-UBI bacterial intracellular accumulation.

The aim of this work was to synthesize [ 166 Dy ] Dy / 166 Ho -DTPA-Biotin to evaluate its potential as a new radiopharmaceutical for targeted radiotherapy. Dysprosium-166 ( 166 Dy ) was obtained by neutron irradiation of enriched 164 Dy 2 O 3 in a Triga Mark III reactor. The labeling was carried out in aqueous media at pH 8.0 by addition of [ 166 Dy ] DyCl 3 to diethylenetriaminepentaacetic-α,ω-bis(biocytinamide) (DTPA-Biotin). Radiochemical purity was determined by high-performance liquid chromatography (HPLC) and TLC. The biological integrity of labeled biotin was studied evaluating its avidity for avidin in an agarose column and by size-exclusion HPLC analysis of the radiolabeled DTPA-Biotin with and without the addition of avidin. Stability studies against dilution were carried out by diluting the radiocomplex solution with saline solution and with human serum at 37 °C for 24 h. The [ 166 Dy ] Dy / 166 Ho -labeled biotin was obtained with a 99.1±0.6% radiochemical purity. In vitro studies demonstrated that [ 166 Dy ] Dy / 166 Ho -DTPA-Biotin is stable after dilution in saline and in human serum and no translocation of the daughter nucleus occurs subsequent to β− decay of 166 Dy that could produce release of 166 Ho 3+ . Avidity of labeled biotin for avidin was not affected by the labeling procedure. Biodistribution studies in normal mice showed that the [ 166 Dy ] Dy / 166 Ho -DTPA-Biotin has a high renal clearance. In conclusion, the radiolabeled biotin prepared in this investigation has adequate properties to work as a stable in vivo generator system for targeted radiotherapy.

Infarct-avid radiopharmaceuticals are necessary for rapid and timely diagnosis of acute myocardial infarction. The animal model used to produce infarction implies artery ligation but chemical induction can be easily obtained with isoproterenol. A new infarct-avid radiopharmaceutical based on glucaric acid was prepared in the hospital radiopharmacy of the INCMNSZ. 99mTc-glucarate was easy to prepare, stable for 96 h and was used to study its biodistribution in rats with isoproterenol-induced acute myocardial infarction. Histological studies demonstrated that the rats developed an infarct 18 h after isoproterenol administration. The rat biodistribution studies showed a rapid blood clearance via the kidneys. Thirty minutes after 99mTc-glucarate administration the standardised heart uptake value ShUV was 4.7 in infarcted rat heart which is six times more than in normal rats. ROIs drawn over the gamma camera images showed a ratio of 4.4. The high image quality suggests that high contrast images can be obtained in humans and the 96 h stability makes it an ideal agent to detect, in patients, early cardiac infarction.

Gold nanoparticles (AuNPs) have been proposed for a variety of medical applications such as localized heat sources for cancer treatment and drug delivery systems. The conjugation of peptides to AuNPs produces stable multimeric systems with target-specific molecular recognition. Lutetium- 177 ((177)Lu) has been successfully used in peptide radionuclide therapy. Recently, (177)Lu-AuNPs conjugated to different peptides have been proposed as a new class of theranostic radiopharmaceuticals. These radioconjugates may function simultaneously as molecular imaging agents, radiotherapy systems and thermal-ablation systems. This article covers advancements in the design, synthesis, physicochemical characterization, molecular recognition assessment and preclinical therapeutic efficacy of gold nanoparticles radiolabeled with (177)Lu and conjugated to RGD (-Arg-Gly-Asp-), Lys(3)-Bombesin and Tat(49-57) peptides.