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The synthesis of reference standards and expected in vivo metabolites of the first adenosine A3 PET radiotracer [18F]FE@SUPPY ([18F]fluoroethyl 4,6-diethyl-5-[(ethyl-sulfanyl)carbonyl]-2-phenylpyridine-3-carboxylate) was achieved by using a straightforward microwave assisted alkylation method, which allowed O/S-chemoselective alkylation of the starting material 1 to give each target compound 2–8 in a single step.

Objectives: Microbial leakage through the implant-abutment (I-A) interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing. Materials and Methods: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants). A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting. Results: Rate of microleakage significantly increased (P≤0.05) in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic) after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading. Conclusions: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic). Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic.

The prediction of in vivo clearance from in vitro metabolism models such as liver microsomes is an established procedure in drug discovery. The potentials and limitations of this approach have been extensively evaluated in the pharmaceutical sector; however, this is not the case for the field of positron emission tomography (PET) radiotracer development. The application of PET radiotracers and classical drugs differs greatly with regard to the amount of substance administered. In typical PET imaging sessions, subnanomolar quantities of the radiotracer are injected, resulting in body concentrations that cannot be readily simulated in analytical assays. This raises concerns regarding the predictability of radiotracer clearance from in vitro data. We assessed the accuracy of clearance prediction for three prototypical PET radiotracers developed for imaging the A1 adenosine receptor (A1AR). Using the half-life (t1/2) approach and physiologically based scaling, in vivo clearance in the rat model was predicted from microsomal stability data. Actual clearance could be accurately predicted with an average fold error (AFE) of 0.78 and a root mean square error (RMSE) of 1.6. The observed slight underprediction (1.3-fold) is in accordance with the prediction accuracy reported for classical drugs. This result indicates that the prediction of radiotracer clearance is possible despite concentration differences of more than three orders of magnitude between in vitro and in vivo conditions. Consequently, in vitro metabolism models represent a valuable tool for PET radiotracer development.

Platelet-derived growth factor receptor β (PDGFRβ) is a transmembrane tyrosine kinase receptor and it is upregulated in various malignant tumors. Radiolabeled PDGFRβ inhibitors can be a convenient tool for the imaging of tumors overexpressing PDGFRβ. In this study, [ 125 I]-1-{5-iodo-2-[5-(2-methoxyethoxy)-1 H -benzo[ d ]imidazol-1-yl]quinoline-8-yl}piperidin-4-amine ([ 125 I]IIQP) and [ 125 I]- N -3-iodobenzoyl-1-{2-[5-(2-methoxyethoxy)-1 H -benzo[ d ]imidazol-1-yl]quinolin-8-yl}-piperidin-4-amine ([ 125 I]IB-IQP) were designed and synthesized, and their potential as PDGFRβ imaging agents was evaluated. In cellular uptake experiments, [ 125 I]IIQP and [ 125 I]IB-IQP showed higher uptake by PDGFRβ-positive cells than by PDGFRβ-negative cells, and the uptake in PDGFRβ-positive cells was inhibited by co-culture with PDGFRβ ligands. The biodistribution of both radiotracers in normal mice exhibited hepatobiliary excretion as the main route. In mice inoculated with BxPC3-luc (PDGFRβ-positive), the tumor uptake of radioactivity at 1 h after the injection of [ 125 I]IIQP was significantly higher than that after the injection of [ 125 I]IB-IQP. These results indicated that [ 125 I]IIQP can be a suitable PDGFRβ imaging agent. However, further modification of its structure will be required to obtain a more appropriate PDGFRβ-targeted imaging agent with a higher signal/noise ratio. [ABSTRACT FROM AUTHOR]

Background: Fast implementation of positron emission tomography (PET) into clinical and preclinical studies highly demands automated synthesis for the preparation of PET radiopharmaceuticals in a safe and reproducible manner. The aim of this study was to develop automated synthesis methods for these six F-labeled radiopharmaceuticals produced on a routine basis at the University of Pennsylvania using the AllinOne synthesis module. Results: The development of automated syntheses with varying complexity was accomplished including HPLC purification, SPE procedures and final formulation with sterile filtration. The six radiopharmaceuticals were obtained in high yield and high specific activity with full automation on the AllinOne synthesis module under current good manufacturing practice (cGMP) guidelines. Conclusion: The study demonstrates the versatility of this synthesis module for the preparation of a wide variety of F-labeled radiopharmaceuticals for PET imaging studies. [ABSTRACT FROM AUTHOR]

In this work, the characteristics of two-phase oil-water flow through a coiled tube geometry have been investigated. Radial mixing, local volume fractions, and phase holdup, over a range of Reynolds numbers of either phase, have been presented. The specific novelty of this work has been the use of time-of-flight (TOF) and volume fraction (VOF) measurements for a single radioactive particle, marked in turn, to represent the flow in either of the phases. This use of the RPT-TOF and RPT-VOF to investigate two-phase oil-water flow has never been reported thus far. In our measurements, a γ -ray emitting radiotracer was made neutrally buoyant with respect to each phase by turn , and subsequently its motion was monitored for its multiple trajectories through coiled geometry, via an array of strategically placed scintillation detectors (NaI(TI)). From the “sojourn times” of the tracer particle through the coiled tube, the characteristic exit age distribution ( E ( t )) and occurrence density distribution were obtained. The former information has related to the velocity field of either phase (RPT-TOF), while the latter information has related to the volume fraction field of either phase (RPT-VOF). Further analysis of this data has revealed interesting features, such as the onset of phase inversion and the distinction of flow regimes. [ABSTRACT FROM AUTHOR]

The current research has been developed in the southern of the Iberian Peninsula in order to better understand the atmospheric processes and also the influence of the air masses origin and pathways in the transport of 210 Pb-aerosols in the atmosphere. Simultaneous measurements of the radionuclides 7 Be and 210 Pb on airborne have been routinely carried out at Granada (Spain 37.177N, 3.598 W, 687 m a.s.l.) from 2010 to 2014. The long term monitoring evolution on 210 Pb is discussed in this study and also the useful ratio 7 Be/ 210 Pb. The maximum monthly activity concentration for 210 Pb at ground level in Granada was detected during summer and early autumn (September), whereas minimum activity was measured in the winter. The monthly mean activity concentration for 210 Pb was 617.8 ± 33.0 μBq·m −3 . The results show that the annual average 210 Pb concentrations in samples collected during the same period were almost constant. The lowest activity concentration for 210 Pb are associated with maritime air masses coming from Atlantic and Norwest of Spain, while the highest activity concentrations for this radiotracers were positively correlated with the arrival of mineral dust linked to continental air masses coming from Mediterranean, Africa and Local area. The concentrations values show a nice agreement with the relevant reported results. [ABSTRACT FROM AUTHOR]

Purpose: Sentinel lymph node biopsy (SLNB) can be used for nodal staging in early cervical cancer. For this purpose, the tracers most commonly used are radiotracers based on technetium. For the last decade, indocyanine green (ICG) has been used as a tracer for SLNB in other malignancies with excellent results and, more recently, a combination of ICG and a radiotracer has been shown to have the advantages of both tracers. The aim of this study was to evaluate the role of ICG-Tc-nanocolloid in SLN detection in patients with cervical cancer. Methods: This prospective study included 16 patients with cervical cancer. The hybrid tracer was injected the day (19-21 h) before surgery for planar and SPECT/CT lymphoscintigraphy. Blue dye was administered periorificially in 14 patients. SLNs were removed according to their distribution on lymphoscintigraphy and when radioactive, fluorescent and/or stained with blue dye. Nodal specimens were pathologically analysed for metastases including by immunochemistry. Results: Lymphoscintigraphy and SPECT/CT showed drainage in all patients. A total of 69 SLNs were removed, of which 66 were detected by their radioactivity signal and 67 by their fluorescence signal. Blue dye identified only 35 SLNs in 12 of the 14 patients (85.7%). All patients showed bilateral pelvic drainage. Micrometastases were diagnosed in two patients, and were the only lymphatic nodes involved. Conclusions: SLNB with ICG-Tc-nanocolloid is feasible and safe in patients with early cervical cancer. This hybrid tracer provided bilateral SLN detection in all patients and a higher detection rate than blue dye, so it could become an alternative to the combined technique. [ABSTRACT FROM AUTHOR]

Flotation tailings from copper production are deposits of copper and other valuable metals, such as Mo, V and U. New hydrometallurgical technologies are more economical and open up new possibilities for metal recovery. This work presents results of the study on the extraction of copper by mixed extractant consisting p-toluidine dissolved in toluene. The possibility of simultaneous liquid-liquid extraction of molybdenum and vanadium was examined. D2EHPA solutions was used as extractant, and recovery of individual elements compared for the representative samples of ore and copper flotation tailings. Radiometric methods were applied for process optimization. [ABSTRACT FROM AUTHOR]

The adsorption of thorium ions on coal has been studied as a function of shaking time, nature of electrolytes (HClO4 , HCl, H2 SO4 and HNO3 ), dose of adsorbent, metal ion concentration and temperature. The radiotracer technique was applied to examine the distribution of thorium using a batch method. Maximum adsorption was found to be at 0.0001 mol L–1 of HNO3 solution, using 0.3 g of adsorbent for 4 mL of 4.310 × 10–5 mol L–1 thorium concentration with equilibration time of 20 min. The adsorption of thorium was decreased with the increase in the concentrations of all the mineral acids used. The kinetic data indicated an intraparticle diffusion process with sorption being pseudo-second-order. The determined rate constant k2 was 13.699 g mg–1 min–1. The adsorption data obeyed the Langmuir, Freundlich and Dubinin–Radushkevich isotherm plots with correlation coefficients (R2 ) of 0.999, 0.986 and 0.994, respectively, over the thorium concentration range of 4.310 × 10–5 to 4.310 × 10–4 mol L–1. The characteristic Freundlich constants such as 1/n = 0.596 and K = 0.706 m mol g–1 whereas the Langmuir constants Q = 4.609 × 10–3 m mol g–1 and b = 17.021 × 10³ dm³ mol–1 have been calculated for the adsorption system. The sorption mean free energy from the Dubinin–Radushkevich isotherm is 10 kJ mol–1 indicating chemical sorption of ion-exchange mechanism. The uptake of thorium was increased with the rise in temperature (283-333 K). Thermodynamic quantities such as DH, DG and DS have been computed and discussed for the system. Sorbent was characterized by using scanning electron microscopy and Fourier transform infrared spectroscopy before and after the adsorption of thorium. Effect of coexistent ions on the adsorption of thorium has also been investigated. By using the optimized parameters the removal of spiked thorium ions from tap water sample was found to be 81.0%. [ABSTRACT FROM AUTHOR]

The ion-exchange kinetics ofAz+sol⇆ Na+mem(Az+= Cs+/Ba2+/Eu3+) in Nafion-117 have been measured using non-stationary radiotracer technique for trace concentrations ofAz+ions in external solution. A method based on non-steady state Nernst–Planck approach has been developed and used to fit the experimental ion-exchange profiles to obtain the diffusion coefficients (DCs) of these ions. The DCs, thus obtained, have been found to be appreciably lower than the literature-reported self-diffusion coefficients, indicating slower rate of ion-exchange. The results show that membrane DCs of these ions are modified by bulk electrolyte solution. [ABSTRACT FROM PUBLISHER]

The increasing incidence of Alzheimer's disease (AD) worldwide is a major public health problem. Current treatments provide only palliative solutions with significant side effects. Therefore, new efficient treatment options and novel early diagnosis tools are urgently needed. Recently, s trong pre-clinical evidences suggested that phosphodiesterase 5 (PDE5) may be clinically relevant both as biomarker and drug-target in AD. In this study, we intended to develop a new radiofluorinated tracer for the visualisation of PDE5 in brain using PET imaging. Based on currently known PDE5 inhibitors, a series of novel fluorinated compounds bearing a quinoline core have been synthesised via multi-steps reaction pathways. Their affinity for PDE5 and selectivity over other PDE families have been investigated. According to the data collected from this in vitro screening, fluorinated derivatives 24a, b bearing a fluoroethoxy group at the C-3 position of the quinoline core appeared to be the most promising structures and will be further radiolabelled with fluorine-18 for in vitro and in vivo evaluations as PET radiotracer for neuroimaging of PDE5. [ABSTRACT FROM AUTHOR]

The article discusses a study on hydrotransport of solid particles (ceramic models of polymetallic nodules) in a vertical pipeline using two different radioisotope methods: tracer and gamma-ray absorption. The radiotracer method makes it possible to determine the velocity of selected solid particles representing specified size fractions while the absorption method enables measurement of mean transport velocity of the entire dispersed phase. The measurements were performed with the use of NaI(Tl) scintillation detectors, sealed linear sources of radiation Am-241 with the energy of 59.54 keV and isotope Tc-99m with gamma radiation energy of 140.51 keV. The experiments were carried out in a pipeline with an internal diameter of 150 mm, for three different water velocities in the range of 1.5–3.6 m/s and three different sizes of ceramic models with size up to 60 mm. Analyses of the detector signals, in measurements based on both tracer and absorption technique, applied cross-correlation function (CCF). It was shown that with the same water velocity different fractions of solid particles have moved with different velocities and the lowest velocities were obtained for the particles with the largest diameters. This enabled interpretation of the CCF in absorption measurements as a distribution of possible interval times for the specific fractions of conveyed particles. [ABSTRACT FROM AUTHOR]

There is often overlap in the diagnostic features of common pathologic processes such as infection, sterile inflammation, and cancer both clinically and using conventional imaging techniques. Here, we report the development of a positron emission tomography probe for live bacterial infection based on the small-molecule antibiotic trimethoprim (TMP). [18F]fluoropropyl-trimethoprim, or [18F]FPTMP, shows a greater than 100-fold increased uptake in vitro in live bacteria (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) relative to controls. In a rodent myositis model, [18F]FPTMP identified live bacterial infection without demonstrating confounding increased signal in the same animal from other etiologies including chemical inflammation (turpentine) and cancer (breast carcinoma). Additionally, the biodistribution of [18F]FPTMP in a nonhuman primate shows low background in many important tissues that may be sites of infection such as the lungs and soft tissues. These results suggest that [18F]FPTMP could be a broadly useful agent for the sensitive and specific imaging of bacterial infection with strong translational potential. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective case review of patients who underwent 18F sodium fluoride PET/CT imaging of the spine with postoperative pain following vertebral fusion.Objective: To determine the benefit of 18F sodium fluoride PET/CT imaging in the diagnosis of persistent pain in the postoperative spine. The diagnosis of pain generators in the postoperative spine has proven to be a diagnostic challenge. The conventional radiologic evaluation of persistent pain after spine surgery with the use of plain radiographs, MRI, and CT can often fall short of diagnosis in the complex patient. 18F sodium fluoride PET/CT imaging is an alternative tool to accurately identify a patient's source of pain in the difficult patient.Methods: This retrospective study looked at 25 adult patients who had undergone 18F sodium fluoride PET/CT imaging. All patients had persistent or recurrent back pain over the course of a 15-month period after having undergone spinal fusion surgery. All patients had inconclusive dedicated MRI. The clinical accuracy of PET/CT in identifying the pain generator and contribution to altering the decision making process was compared to the use of CT scan alone.Results: Of the 25 patients studied, 17 patients had increased uptake on the 18F sodium fluoride PET/CT fusion images. There was a high-level correlation of radiotracer uptake to the patients' pain generator. Overall 88% of the studies were considered beneficial with either PET/CT altering the clinical diagnosis and treatment plan of the patient or confirming unnecessary surgery.Conclusion: 18F sodium fluoride PET/CT proves to be a useful tool in the diagnosis of complex spine pathology of the postoperative patients. In varied cases, a high correlation of metabolic activity to the source of the patient's pain was observed. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop three new radiotracers, 1-(cyclopropylmethyl)-4-([ 11 C/ 18 F]substituted-phenyl)piperidin-1-yl-2-oxo-1,2-dihydropyridine-3-carbonitrile ([ 11 C] 1 , [ 11 C] 2 , and [ 18 F] 4 ), and to examine their specific bindings with metabotropic glutamate receptor subtype 2 (mGluR2) in rat brain sections by using in vitro autoradiography. These compounds were found to possess potent in vitro binding affinities ( K i : 8.0–34.1 nM) for mGluR2 in rat brain homogenate. [ 11 C] 1 , [ 11 C] 2 , and [ 18 F] 4 were synthesized by [ 11 C/ 18 F]alkylation of the corresponding phenol precursors with [ 11 C]methyl iodide or [ 18 F]fluoroethyl bromide with >98% radiochemical purity and 80–130 GBq/μmol specific activity at the end of synthesis. In vitro autoradiography indicated that these radiotracers showed heterogeneous specific bindings in mGluR2-rich brain regions, such as the cerebral cortex, striatum, hippocampus, and granular layer of the cerebellum. [ABSTRACT FROM AUTHOR]

This paper communicates the synthesis of a new functionalized adsorbent and its applications as an efficient extractant for economically important Ag(II) metal. The functionalized adsorbent is synthesized through covalent attachment of a chelating compound thiosemicarbazide to the silica surface through modification route. Various characterization techniques such as Fourier transform infrared spectroscopy, Thermogravimetric analysis and Energy-dispersive X-ray spectroscopy confirmed that the ligand is successfully attached to the silica surface. The performance of the synthesized adsorbent is evaluated in batch adsorption experiments using radiotracer procedure. Rate transfer and thermodynamic factors are studied to ensure the practical use of the adsorbent for Ag(II) ions removal. The adsorption of Ag(II) followed first-order rate equation and is controlled by surface and intraparticle diffusions. Thermodynamic studies revealed that the Ag(II) adsorption is spontaneous (?G = -5,639.32 J/mol) and favorable (?S = 85.08 J/mol K). The equilibrium adsorption data followed Langmuir, Freundlich and D-R equations and from these models ion-exchange parameters are computed. The sorbent can be easily regenerated and used several times for Ag(II) ions adsorption. [ABSTRACT FROM AUTHOR]

Diffusion of Ag in Cu(In,Ga)Se 2 was investigated utilizing radiotracer sputter-profiling of 110m Ag. After removal of the CdS capping layer the 110m Ag isotope was deposited on the front-surface of the Cu(In,Ga)Se 2 layer and the samples were subjected to isothermal annealing in a temperature interval ranging from 573 K up to 648 K. The observed Ag diffusivity can be described by the following Arrhenius equation D(T) = 0.12 exp (− 1.29 eV/k B T) cm 2 /s . Comparison with the diffusivities of Zn, Cd and Fe in Cu(In,Ga)Se 2 in the investigated temperature regime reveals similiar activation energies, but a larger pre-exponential factor for Ag diffusion resulting in accelerated diffusion kinetics. [ABSTRACT FROM AUTHOR]

This study describes a convenient protocol for the synthesis of (2S)-tert-butyl 2-(2-bromopropanamido)-5-oxo-5-(tritylamino)pentanoate, which can serve as an appropriate precursor of (2S)-5-amino-2-(2-[18F]fluoropropanamido)-5-oxopentanoic acid (N-(2-[18F]fluoropropionyl)-L-glutamine, [18F]FPGLN) for tumor positron emission tomography imaging. Five-step synthesis starting fromL-glutamine provided the desired precursor with high yields. In addition, a simple method for the preparation of [18F]FPGLN from this easily available precursor was developed using a two-step18F-labeling strategy. [ABSTRACT FROM PUBLISHER]

Flow dynamics of heavy petroleum residue in an industrial-scale soaker operating in a petroleum refinery was investigated. Residence time distributions (RTDs) of the residue were measured using radiotracer technique. Bromine-82 as dibromobiphenyl was used as radiotracer for tracing the petroleum residue. The measured RTDs were treated and mean residence times (MRTs) were determined. The measured RTD data was simulated using a combined model i.e. axial dispersion model in parallel with tanks-in-series with stagnant volume and exchange. The results of the model simulation fitted very well to the experimentally measured data and identified bypassing or existence two parallel flow paths within the soaker. [ABSTRACT FROM AUTHOR]

Immune checkpoint inhibitor therapy (ICT) is a new treatment strategy developed for the treatment of cancer. ICT inhibits pathways known to downregulate the innate immune response to cancer cells. These drugs have been shown to be effective in the treatment of a variety of cancers, including metastatic melanoma and lung cancer. Challenges in response evaluation of patients in ICT have risen as immune related side effects and immune cell infiltration may be confused with progressive disease. Furthermore, the timing of the evaluation scan may be challenged by relatively slow responses. To overcome this, new response criteria for evaluating these patients with morphologic imaging have been proposed. The aim of this paper is to review and discuss the current evidence for the use of molecular imaging, e.g., PET/CT (Positron Emission Tomography/Computer Tomography) with 18F-Fluorodeoxyglucoes (FDG) as an alternative imaging method for monitoring patients undergoing ICT. Following the currently available evidence, this review will primarily focus on patients with malignant melanoma. [ABSTRACT FROM AUTHOR]

The urokinase-type plasminogen activator receptor (uPAR) is overexpressed in several cancers including glioblastoma (GBM) and is an established biomarker for metastatic potential. The uPAR-targeting peptide AE105-NH (Ac-Asp-Cha-Phe-(D)Ser-(D)Arg-Tyr-Leu-Trp-Ser-CONH) is a promising candidate for non-invasive positron emission tomography (PET) imaging of uPAR. Despite the optimal physical properties of Ga for peptide-based PET imaging, low tumor uptakes have previously been reported using Ga-labeled AE105-NH-based tracers. In an attempt to optimize the tumor uptake, we developed three novel tracers with alkane (AOC) and polyethylene glycol (PEG) spacers inserted between AE105-NH and the radio metal chelator 2-(4,7-bis(carboxymethyl)-1,4,7-triazonan-1-yl)pentanedioic acid (NODAGA). The resulting tracers NODAGA-AOC-AE105-NH, NODAGA-PEG-AE105-NH and NODAGA-PEG-AE105-NH were compared to the non-spacer version, NODAGA-AE105-NH. Following radiolabeling with Ga, we evaluated the in vitro and in vivo performance in mice bearing subcutaneous tumors derived from the uPAR-expressing human GBM cell line U87MG. In vivo PET/CT imaging showed that introduction of PEG spacers more than doubled the in vivo tumor uptake after 1 h compared with the non-spacer version: Ga-NODAGA-PEG-AE105-NH (2.08 ± 0.37%ID/g) and Ga-NODAGA-PEG-AE105-NH (2.01 ± 0.22%ID/g) vs. Ga-NODAGA-AE105-NH (0.70 ± 0.40%ID/g), p < 0.05. In addition, Ga-NODAGA-PEG-AE105-NH showed significantly higher ( p < 0.05) tumor-to-background contrast (3.68 ± 0.23) than the other tracers. The specific tumor-targeting property of Ga-NODAGA-PEG-AE105-NH was established by effectively blocking the tumor uptake with co-injection of unlabeled AE105-NH (1 h: unblocked 2.01 ± 0.22%ID/g vs. blocked 1.24 ± 0.09%ID/g, p < 0.05). Ex vivo biodistribution confirmed the improved tumor uptakes of the PEG-modified tracers. Ga-NODAGA-PEG-AE105-NH is thus a promising candidate for human translation for PET imaging of GBM. [ABSTRACT FROM AUTHOR]

This paper describes a systematic study carried out to investigate adsorption characteristics of 198 Au onto the surface of coal particles using a radiotracer technique. The main objective of the study was to optimize labeling conditions and utilize the labeled coal particles as a radiotracer for tracing coal particles in fluidized bed coal gasifiers. The effect of various experimental factors such as pH, amount of adsorbent, initial gold concentration, temperature and contact time between adsorbate and adsorbent were studied to obtain optimum conditions for maximum adsorption of 198 Au on coal particles from an aqueous solution. Analysis of the data showed that the Langmuir model was found most suitable to describe the adsorption phenomena. The thermodynamic analysis showed that the adsorption process is feasible, spontaneous and endothermic in nature. The results of the kinetics suggested that the adsorption presumably follows second order kinetics and chemisorption in nature. Based on the optimized conditions, the amount of coal particles and activity to be used for tracing the coal phase in pilot-scale gasifiers was estimated. Accordingly, the radiotracer was prepared and successfully used for measurement of residence time distribution (RTD) in a pilot-scale coal gasifier. [ABSTRACT FROM AUTHOR]

Honey bees ( Apis mellifera ) are generalist pollinators that forage for nectar and pollen of a very large variety of plant species, exposing them to a diverse range of secondary metabolites produced as chemical defences against herbivory. Honey bees can tolerate high levels of many of these toxic compounds, including the alkaloid nicotine, in their diet without incurring apparent fitness costs. Very little is known about the underlying detoxification processes mediating this tolerance. We examined the metabolic fate of nicotine in newly emerged worker bees using radiolabeled nicotine and LC-MS/MS analysis to determine the kinetic distribution profile of nicotine as well as the absence or presence and identity of any nicotine-derived metabolites. Nicotine metabolism was extensive; virtually no unmetabolised nicotine were recovered from the rectum. The major metabolite found was 4-hydroxy-4-(3-pyridyl) butanoic acid, the end product of 2′C-oxidation of nicotine. It is the first time that 4-hydroxy-4-(3-pyridyl) butanoic acid has been identified in an insect as a catabolite of nicotine. Lower levels of cotinine, cotinine N-oxide, 3′hydroxy-cotinine, nicotine N-oxide and norcotinine were also detected. Our results demonstrated that formation of 4-hydroxy-4-(3-pyridyl) butanoic acid is quantitatively the most significant pathway of nicotine metabolism in honey bees and that the rapid excretion of unmetabolised nicotine does not contribute significantly to nicotine tolerance in honey bees. In nicotine-tolerant insects that do not rely on the rapid excretion of nicotine like the Lepidoptera, it is possible that the 2′C-oxidation of nicotine is the conserved metabolic pathway instead of the generally assumed 5′C-oxidation pathway. [ABSTRACT FROM AUTHOR]

Objective: This Phase 2 study assessed the performance of positron emission tomography (PET) brain images made with Flutemetamol F 18 Injection in detecting β-amyloid neuritic plaques in Japanese subjects.Methods: Seventy subjects (25 with probable Alzheimer's disease (pAD), 20 with amnestic mild cognitive impairment (aMCI), and 25 cognitively normal healthy volunteers[HVs]) underwent PET brain imaging after intravenous Flutemetamol F 18 Injection (185 MBq). Images were interpreted as normal or abnormal for neuritic plaque density by each of five non-Japanese and five Japanese readers who were blinded to clinical data. The primary efficacy analysis (based on HV and pAD data) was the agreement of the non-Japanese readers' image interpretations with the clinical diagnosis, resulting in estimates of positive percent agreement (PPA; based on AD subjects; similar to sensitivity) and negative percent agreement (NPA; based on HVs; similar to specificity). Secondary analyses included PPA and NPA for the Japanese readers; inter-reader agreement (IRA); intra-reader reproducibility (IRR); quantitative image interpretations (standardized uptake value ratios [SUVRs]) by diagnostic subgroup; test-retest variability in five pAD subjects; and safety.Results: PPA was 92% for all non-Japanese readers and ranged from 88 to 92% for the Japanese readers. NPA ranged from 96 to 100% for both the non-Japanese readers and the Japanese readers. The majority image interpretations (the interpretations made independently by ≥3 of 5 readers) resulted in PPA values of 92 and 92% and NPA values of 100 and 96% for the non-Japanese and Japanese readers, respectively. IRA and IRR were strong. Composite SUVR values (mean of multiple regional values) allowed clear differentiation between pAD subjects and HVs. Test-retest variability ranged from 1.14 to 2.27%, and test-retest agreement of the blinded visual interpretations was 100% for all readers. Flutemetamol F 18 Injection was generally well tolerated.Conclusions: The detection of brain neuritic plaques in Japanese subjects using [18F]Flutemetamol PET images gave results highly consistent with clinical diagnosis, with non-Japanese and Japanese readers giving similar results. Inter-reader agreement and intra-reader reproducibility were high for both sets of readers. Visual delineation of abnormal and normal scans was corroborated by quantitative assessment, with low test-retest variability.Trial Registration: Clinicaltrials.gov registration number NCT02813070. [ABSTRACT FROM AUTHOR]

Holdup and axial dispersion of liquid phase in a catalytic exchange column were investigated by measuring residence time distributions (RTD) using a radiotracer technique. RTD experiments were independently carried out with two different types of packings i.e. hydrophobic water-repellent supported platinum catalyst and a mixture (50% (v/v)) of hydrophobic catalyst and a hydrophillic wettable packing were used in the column. Mean residence times and hold-ups of the liquid phase were estimated at different operating conditions. Axial dispersion model (ADM) and axial dispersion with exchange model (ADEM) were used to simulate the measured RTD data. Both the models were found equally suitable to describe the measured data. The degree of axial mixing was estimated in terms of Peclet number (Pe) and Bodenstein number (Bo). Based on the obtained parameters of the ADM, correlations for total liquid hold-up (H T ) and axial mixing in terms of Bo were proposed for design and scale up of the full-scale catalytic exchange column. [ABSTRACT FROM AUTHOR]

Introduction Anandamide (N-arachidonoylethanolamine) is a retrograde neuromodulator that activates cannabinoid receptors. The concentration of anandamide in the brain is controlled by fatty acid amide hydrolase (FAAH), which has been the focus of recent drug discovery efforts. Previous studies in C57BL/6 mice using [ 3 H-arachidonoyl]anandamide demonstrated deposition of tritium in thalamus and cortical areas that was blocked by treatment with an FAAH inhibitor and that was not seen in FAAH-knockout mice. This suggested that long chain fatty acid amides radiolabeled in the fatty acid moiety might be useful as ex vivo and in vivo radiotracers for FAAH, since labeled fatty acid released by hydrolysis would be rapidly incorporated into phospholipids with long metabolic turnover periods. Methods Radiotracers were administered intravenously to conscious Swiss–Webster mice, and radioactivity concentrations in brain areas was quantified and radiolabeled metabolites determined by radiochromatography. Results [ 14 C]Arachidonic acid, [ 14 C-arachidonoyl]anandamide and [ 14 C-ethanolamine]anandamide, and also [ 14 C]myristic acid, [ 14 C-myristoyl]myristoylethanolamine and [ 14 C-ethanolamine]myristoyl-ethanolamine all had very similar distribution patterns, with whole brain radioactivity concentrations of 2–4% injected dose per gram. Pretreatment with the potent selective FAAH inhibitor URB597 did not significantly alter distribution patterns although radiochromatography demonstrated that the rate of incorporation of label from [ 14 C]anandamide into phospholipids was decreased. Pretreatment with the muscarinic agonist arecoline which increases cerebral perfusion increased brain uptake of radiolabel from [ 14 C]arachidonic acid and [ 14 C-ethanolamine]anandamide, and (in dual isotope studies) from the unrelated tracer [ 125 I]RTI-55. Conclusions Together with our previously published study with [ 18 F-palmitoyl]16-fluoro-palmitoylethanolamine, the data show that the primary determinant of brain uptake for these tracers in Swiss–Webster mice is initial distribution according to blood flow. It is possible that recently reported strain differences in long chain fatty acid trafficking between C57BL/6 and Swiss–Webster mice are responsible for the differences between our results using [ 14 C]anandamide and the earlier studies using [ 3 H]anandamide. [ABSTRACT FROM AUTHOR]

Brain metabotropic glutamate receptor 2 (mGluR2) has been proposed as a therapeutic target for the treatment of schizophrenia-like symptoms arising from increased glutamate transmission in the forebrain. However, there does not exist a reliable tool for the study of mGluR2 in human neuroimaging. The purpose of this study was to radiosynthesize 1-(cyclopropylmethyl)-4-(4-[ 11 C]methoxyphenyl)piperidin-1-yl-2-oxo-1,2-dihydropyridine-3-carbonitrile ([ 11 C]CMDC) and evaluate its potential as a positron emission tomography (PET) radiotracer for imaging mGluR2 in the rat brain. CMDC, a positive allosteric modulator of mGluR2, showed potent functional activity (EC 50 : 98 nM) for human mGluR2 in vitro. [ 11 C]CMDC was synthesized by O -[ 11 C]methylation of 1-(cyclopropylmethyl)-4-(4-hydroxyphenyl)piperidin-1-yl-2-oxo-1,2-dihydropyridine-3-carbonitrile ( 1 ) with [ 11 C]methyl iodide. [ 11 C]CMDC (2.2 ± 0.9 GBq; n = 20) was obtained from [ 11 C]CO 2 of 14.0–17.8 GBq with >98% radiochemical purity and 86–150 GBq/μmol specific activity at the end of synthesis. In vitro autoradiography indicated that [ 11 C]CMDC binding was expressed (>50% of total binding) in mGluR2-rich brain regions including the cerebral cortex, striatum and hippocampus. However, small-animal PET showed low in vivo specific binding of [ 11 C]CMDC in the rat brain. While [ 11 C]CMDC has limited potential as a PET tracer for brain mGluR2, it can be used to develop new radiotracers with improved behaviors. [ABSTRACT FROM AUTHOR]

Recent studies have shown Hg methylation in mangrove sediments, however, little is known about the different microorganism consortia involved. We investigated the participation of prokaryotes in general, iron-reducing bacteria-IRB, sulfate-reducing bacteria-SRB, methanogens and fungi in Hg methylation and sulfate reduction rates (SRR) in mangrove sediments using iron amendments for IRB and specific inhibitors for the other microorganisms. Sediment samples were collected from two mangrove zones, tidal flat and mangrove forest (named root sediments). Samples were incubated with 203 Hg or 35 SO 4 2− and Me 203 Hg/ 35 Sulfur were measured by liquid scintillation. Methylmercury (MeHg) formation was significantly reduced when SRB (87.7%), prokaryotes (76%) and methanogens (36.5%) were inhibited in root sediments, but only SRB (51.6%) and prokaryotes (57.3%) in tidal flat. However, in the tidal flat, inhibition of methanogens doubled Hg methylation (104.5%). All inhibitors (except fungicide) significantly reduced SRR in both zones. In iron amended tidal flat samples, Hg methylation increased 56.5% at 100 μg g −1 and decreased at 500 and 1000 μg g −1 (57.8 and 82%). In the roots region, however, MeHg formation gradually decreased in response to Fe amendments from 100 μg g −1 (37.7%) to 1000 μg g −1 (93%). SRR decreased in all iron amendments. This first simultaneous evaluation of Hg methylation and sulfate-reduction and of the effect of iron and inhibitors on both processes suggest that SRB are important Hg methylators in mangrove sediments. However, it also suggests that SRB activity could not explain all MeHg formation. This implies the direct or indirect participation of other microorganisms such as IRB and methanogens and a complex relationship among these groups. [ABSTRACT FROM AUTHOR]

Introduction Aspects of radiopharmaceutical development are illustrated through preclinical studies of [ 125 I]-( E )-1-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-4-(iodoallyl)piperazine ([ 125 I]- E -IA-BF-PE-PIPZE), a radioligand for sigma-1 (σ 1 ) receptors, coupled with examples from the recent literature. Findings are compared to those previously observed for [ 125 I]-( E )-1-(2-(2,3-dimethoxy-5-yl)ethyl)-4-(iodoallyl)piperazine ([ 125 I]- E -IA-DM-PE-PIPZE). Methods Syntheses of E -IA-BF-PE-PIPZE and [ 125 I]- E -IA-BF-PE-PIPZE were accomplished by standard methods. In vitro receptor binding studies and autoradiography were performed, and binding potential was predicted. Measurements of lipophilicity and protein binding were obtained. In vivo studies were conducted in mice to evaluate radioligand stability, as well as specific binding to σ 1 sites in brain, brain regions and peripheral organs in the presence and absence of potential blockers. Results E -IA-BF-PE-PIPZE exhibited high affinity and selectivity for σ 1 receptors ( K i = 0.43 ± 0.03 nM, σ 2 /σ 1 = 173). [ 125 I]- E -IA-BF-PE-PIPZE was prepared in good yield and purity, with high specific activity. Radioligand binding provided dissociation (k off ) and association (k on ) rate constants, along with a measured K d of 0.24 ± 0.01 nM and B max of 472 ± 13 fmol/mg protein. The radioligand proved suitable for quantitative autoradiography in vitro using brain sections. Moderate lipophilicity, Log D 7.4 2.69 ± 0.28, was determined, and protein binding was 71 ± 0.3%. In vivo, high initial whole brain uptake, >6% injected dose/g, cleared slowly over 24 h. Specific binding represented 75% to 93% of total binding from 15 min to 24 h. Findings were confirmed and extended by regional brain biodistribution. Radiometabolites were not observed in brain (1%). Conclusions Substitution of dihydrobenzofuranylethyl for dimethoxyphenethyl increased radioligand affinity for σ 1 receptors by 16-fold. While high specific binding to σ 1 receptors was observed for both radioligands in vivo, [ 125 I]- E -IA-BF-PE-PIPZE displayed much slower clearance kinetics than [ 125 I]- E -IA-DM-PE-PIPZE. Thus, minor structural modifications of σ 1 receptor radioligands lead to major differences in binding properties in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Iodobenzamides are reported to possess some affinity for melanoma. This study describes the synthesis of a new benzamide analogue, N-(2-diethylamino-ethyl)-4-(4-chloro-nicotinamido)-5-[125I]iodo-2-methoxybenzamide ([125I] H4) designed to target melanoma. The synthesis was simply achieved in four steps. There were two PyCIU/DIPEA amide condensations and a transfer hydrogenation using an ammonium formate hydrogen donor. The radioiodination step was carried out with 125I via an electrophilic substitution reaction. The reaction conditions were optimized. The labeled compound was purified by HPLC. The maximum radiochemical yield was found to be 78% at a radiochemical purity of 98%. All compounds were characterized by MS and NMR techniques. The log P value for [125I] H4 was found as 3.96±0.5. [ABSTRACT FROM AUTHOR]

Radiotracer techniques are widely used for troubleshooting and detection of pathological flows in industrial reactors. In recent decades, there has been a trend towards using radiotracer techniques for assessing flow field in industrial vessels, likening them to residence time distribution (RTD) measurements. On the other hand, radiation-based particle tracking techniques such as Radioactive Particle Tracking (RPT) methods have become popular for laboratory investigations flow fields in multiphase reactors. Both the methods have been used to validate respective-scale phenomenological and CFD models to some success, but in a rather independent and ad hoc fashion and not attempting to link the two techniques as flow interrogators in their respective domains. This communication tries to bridge these two techniques and proposes a way to link the two, and makes a case for using them as complementary techniques for measurements at the two scales, and for validating models at the two scales. © 2016 American Institute of Chemical Engineers AIChE J, 63: 314-326, 2017 [ABSTRACT FROM AUTHOR]

Breast cancer is the most frequent cancer in women and it is the main reason of cancer-related deaths of women worldwide. Different types of breast cancer diagnostic examinations are also available, such as mammography, MRI, biopsy, ultrasound and molecular imaging. Radionuclide-based imaging methods including SPECT and PET are useful in early diagnosis and treatment of the cancer. The radiolabeling of chemo drugs with nanoparticles should be recommended from the standpoint of an early diagnosis and effective treatment of breast cancer. [ABSTRACT FROM AUTHOR]

With the introduction of automated synthetization methods, the in-house production of several 68Ga-based tracers became feasible in hospital laboratories. We describe a possible standard operating procedure (SOP) for [68Ga]Ga-oxine-labeled heat-denaturated erythrocytes, which can be used for selective imaging in patients with splenic disorders. Heat-denaturated erythrocytes were labeled with [68Ga]Ga-oxine, which was produced from 68Ga and 8-hydroxyquinoline on an automated synthesizer. The workflow was validated in a good manufacturing/good radiopharmaceutical practice (GMP/GRP) certified laboratory. A patient underwent [68Ga]Ga-oxine-erythrocyte PET/CT for differentiation of an intrapancreatic mass. [68Ga]Ga-oxine and [68Ga]Ga-oxine-labeled erythrocytes could be synthesized reproducibly and reliably. The products met GMP quality standards. The tracer showed high accumulation in the intrapancreatic mass, consistent with an accessory spleen. PET/CT imaging with [68Ga]Ga-oxine-labeled, heat-denaturated erythrocytes can be a backup method for the differentiation of functioning splenic tissue from tumors. An SOP for the production of the tracer in a clinical setting could be established. [ABSTRACT FROM AUTHOR]

A radiotracer investigation was previously carried out to characterize the flow of the molten glass and to identify the cause of poor quality of the glass sheets produced in an industrial solar glass production unit (SGPU-1) (Pant et al., 2016). Based on the investigations, several flow abnormalities were identified and the design of the unit was modified to improve the quality of the product and meet the product specifications. Subsequently, the radiotracer investigation was repeated in the modified unit (SGPU-1m). The results of the study showed that the dead volume and homogenization time in the modified unit were significantly reduced with improvement in mixing of the molten glass as compared to the SGPU-1. Based on the results of the two investigations, a new glass production unit (SGPU-2) with enhanced capacity was designed, fabricated and commissioned. The radiotracer investigation was repeated in the newly designed unit with an objective to evaluate and validate its design. The results indicated that the performance of SGPU-2 was as per the design criteria and the quality of the glass sheets produced was as per the desired specifications. • Radiotracer investigations were carried out in two different solar glass production units. • La-140 was used as radiotracer to measure residence time distributions of molten glass. • Flow parameters of molten glass were estimated and designs of units were evaluated. • Suitable flow models were developed to describe the flow of the molten glass. [ABSTRACT FROM AUTHOR]

Blockages in pipelines inhibit the normal use of the pipeline due to constricted flow of fluid through the pipeline. Locating blockages in pipelines is a challenge and there is an increasing demand for sensitive inspection methods to locate blockages in pipelines, caused either due to presence of foreign undesired material during commissioning or maintenance of the pipeline or due to accumulation of product remanent during the prolonged use of the pipelines. A block was caused in a multiproduct pipeline due to a stuck pig (pipe inspection gauge). Radiotracer techniques viz. gamma scanning and radiography were employed to pinpoint the block location. • Blockage detection in pipelines using radioisotopes. • Gamma scanning for monitoring and evaluating pipeline conditions. • Locating stuck pipe inspection gauge in a pipeline using gamma scanning. • Radiography technique for locating pipe inspection gauge stuck in a pipeline. • Combination of radioisotope techniques for pin pointing the block location in pipeline. [ABSTRACT FROM AUTHOR]

• Cd uptake rate increased in fish after acute exposure to Cd and B[a]P. • B[a]P uptake rate increased in fish simultaneously exposed to Cd and B[a]P. • Higher Cd uptake rate does not correspond to higher expression of gill transporters. Cadmium and Benzo[a]pyrene are two toxicants of great environmental importance given their frequency and ability to cause extensive toxicity in aquatic organisms including fish. There is evidence that fish can modulate their respective uptake rate during simultaneous exposures, albeit the mechanism behind this is poorly understood. The present study aimed to examine this interaction by exposing adult zebrafish to either 89.3 nM Cd, 4.25 nM BaP or a combination of the two for 72 hrs prior to examining the uptake rate of either toxicant via short-term exposures (3–6 hrs) to radiotracers (109Cd and 14C-BaP). Our results showed that Cd uptake rate increased significantly in the gills when animals were pre-exposed to both toxicants simultaneously, resulting in an increased maximum uptake rate (Jmax). The increased Cd uptake rate did not correspond to increased expression of gill Cd transporters such as the epithelium calcium channel (ECaC) or the divalent metal transporter 1 (DMT1). Furthermore, BaP uptake rate increased significantly at the whole-body level when animals were exposed to both 5.03 nM 14C-BaP and 89.3 nM Cd concurrently. Additionally, we ran a time-course and observed BaP uptake rate is highest in the 6–12 hrs following the beginning of the exposure. Our results provide evidence that the increased bioaccumulation of Cd and BaP observed during co-exposures is at least in part due to an increase in uptake rate and is driven by separate mechanisms. [ABSTRACT FROM AUTHOR]

The microplastics amount in the environment is significantly increasing due to human activity, and the hazards are still being investigated. To evaluate the fate of microplastics in organisms, an accurate, fast, and sensitive method is required. Nuclear technology harnessing radiotracer is one of the most sensitive and accurate method for bioaccumulation, biodistribution and biokinetic study. Here, we developed a preparation method for radioiodinated polyvinyl chloride (PVC) as a potential radiotracer of microplastics. Iodine-131 (131I) as a potential radiotracer for microplastic was used in this experiment (activity of 98.05–221.63 MBq). The 131I-PVC was prepared using the Conant-Finkelstein reaction with a solvent combination of phosphate buffer (B), acetone (A), and tetrahydrofuran (T). Such preparation method resulted in spherical 131I-PVC with sizes ranging from 608.6 to 5457.0 nm. Our study showed that acetone is the most suitable solvent for the radioiodination process, resulting in a stable 131I-PVC for up to six days. • Radiolabelled micro-PVC is required for bioaccumulation study in marine biota. • Production of micro-PVC-131I based on the Conant-Finkelstein reaction • Stability of micro-PVC-131I sufficient for bioaccumulation study on marine biota [ABSTRACT FROM AUTHOR]

The anaerobic digesters find usage in treating the huge amount of waste such as trash, garbage, human waste and animal waste. The sustained performance of an anaerobic digester depends on the flow pattern and mixing behaviour in the digester. A cylindrical digester tank with vertical baffles can provide flow behaviour approaching that of a plug flow reactor. However, the presence of dead zones and recirculating regions cause non-ideal flow in the digester. In this work, the mixing behaviour in two scaled-down models of baffled digester tanks is characterized by measurement of residence time distribution (RTD) using a radioactive tracer. While the first design has three vertical baffles, the second design include horizontal static flaps on the baffles. The flow behaviour in the digester is also simulated using computational fluid dynamics (CFD) and RTD is obtained computationally. The comparison of RTD curves obtained from CFD simulations with those obtained from radiotracer experiments show good agreement between them. There appear to be only minor difference in the flow behaviour and the RTD curves in the two digester designs. Using the RTD curve data, two commonly used RTD models, tank-in-series and dispersion models, have been fitted and both models are able to predict the RTD in the digester qualitatively. • Residence time distribution in a laboratory scale digester is investigated. • Details of the hydrodynamics is investigated using CFD. • CFD modeling and radiotracer methodologies are used. • RTD data fitted with the tank-in-series and dispersion models. [ABSTRACT FROM AUTHOR]