Localization of infection in neonatal rhesus macaques after oral viral challenge.

Vertical transmission of human immunodeficiency virus (HIV) can occur in utero, during delivery, and through breastfeeding. We utilized Positron Emission Tomography (PET) imaging coupled with fluorescent microscopy of 64Cu-labeled photoactivatable-GFP-HIV (PA-GFP-BaL) to determine how HIV virions distribute and localize in neonatal rhesus macaques two and four hours after oral viral challenge. Our results show that by four hours after oral viral exposure, HIV virions localize to and penetrate the rectal mucosa. We also used a dual viral challenge with a non-replicative viral vector and a replication competent SHIV-1157ipd3N4 to examine viral transduction and dissemination at 96 hours. Our data show that while SHIV-1157ipd3N4 infection can be found in the oral cavity and upper gastrointestinal (GI) tract, the small and large intestine contained the largest number of infected cells. Moreover, we found that T cells were the biggest population of infected immune cells. Thus, thanks to these novel technologies, we are able to visualize and delineate of viral distribution and infection throughout the entire neonatal GI tract during acute viral infection.

Copper Coordination Chemistry of Sulfur Pendant Cyclen Derivatives: An Attempt to Hinder the Reductive-Induced Demetalation in 64/67Cu Radiopharmaceuticals.

The Cu2+ complexes formed by a series of cyclen derivatives bearing sulfur pendant arms, 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO3S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-10-acetamido-1,4,7,10-tetraazacyclododecane (DO3SAm), and 1,7-bis[2-(methylsulfanyl)ethyl]-4,10-diacetic acid-1,4,7,10-tetraazacyclododecane (DO2A2S), were studied in aqueous solution at 25 °C from thermodynamic and structural points of view to evaluate their potential as chelators for copper radioisotopes. UV-vis spectrophotometric out-of-cell titrations under strongly acidic conditions, direct in-cell UV-vis titrations, potentiometric measurements at pH >4, and spectrophotometric Ag+-Cu2+ competition experiments were performed to evaluate the stoichiometry and stability constants of the Cu2+ complexes. A highly stable 1:1 metal-to-ligand complex (CuL) was found in solution at all pH values for all chelators, and for DO2A2S, protonated species were also detected under acidic conditions. The structures of the Cu2+ complexes in aqueous solution were investigated by UV-vis and electron paramagnetic resonance (EPR), and the results were supported by relativistic density functional theory (DFT) calculations. Isomers were detected that differed from their coordination modes. Crystals of [Cu(DO4S)(NO3)]·NO3 and [Cu(DO2A2S)] suitable for X-ray diffraction were obtained. Cyclic voltammetry (CV) experiments highlighted the remarkable stability of the copper complexes with reference to dissociation upon reduction from Cu2+ to Cu+ on the CV time scale. The Cu+ complexes were generated in situ by electrolysis and examined by NMR spectroscopy. DFT calculations gave further structural insights. These results demonstrate that the investigated sulfur-containing chelators are promising candidates for application in copper-based radiopharmaceuticals. In this connection, the high stability of both Cu2+ and Cu+ complexes can represent a key parameter for avoiding in vivo demetalation after bioinduced reduction to Cu+, often observed for other well-known chelators that can stabilize only Cu2+.

Imaging Neurotensin Receptor in Prostate Cancer With 64Cu-Labeled Neurotensin Analogs.

INTRODUCTION: Neurotensin receptor 1 (NTR-1) is expressed and activated in prostate cancer cells. In this study, we explore the NTR expression in normal mouse tissues and study the positron emission tomography (PET) imaging of NTR in prostate cancer models. MATERIALS AND METHODS: Three 64Cu chelators (1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid [DOTA], 1,4,7-triazacyclononane-N,N',N″-triacetic acid [NOTA], or AmBaSar) were conjugated to an NT analog. Neurotensin receptor binding affinity was evaluated using cell binding assay. The imaging profile of radiolabeled probes was compared in well-established NTR+ HT-29 tumor model. Stability of the probes was tested. The selected agents were further evaluated in human prostate cancer PC3 xenografts. RESULTS: All 3 NT conjugates retained the majority of NTR binding affinity. In HT-29 tumor, all agents demonstrated prominent tumor uptake. Although comparable stability was observed, 64Cu-NOTA-NT and 64Cu-AmBaSar-NT demonstrated improved tumor to background contrast compared with 64Cu-DOTA-NT. Positron emission tomography/computed tomography imaging of the NTR expression in PC-3 xenografts showed high tumor uptake of the probes, correlating with the in vitro Western blot results. Blocking experiments further confirmed receptor specificity. CONCLUSIONS: Our results demonstrated that 64Cu-labeled neurotensin analogs are promising imaging agents for NTR-positive tumors. These agents may help us identify NTR-positive lesions and predict which patients and individual tumors are likely to respond to novel interventions targeting NTR-1.

Chelator-Free and Biocompatible Melanin Nanoplatform with Facile-Loading Gadolinium and Copper-64 for Bioimaging.

Development of a chelator-free and biocompatible platform for the facile construction of gadolinium3+ (Gd3+)-loaded nanoparticle based probes for in vivo magentic resonance imaging (MRI) is still challenging. Herein, biocompatible Gd3+-loading melanin dots (Gd-M-dots) have been easily prepared and have exhibited good loading efficiency for Gd3+, high stability, and higher T1 relaxivity compared to the commercial Gd-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) agent. Furthermore, Gd-M-dots showed unique photoacoustic (PA) properties, and a high PA imaging signal could be observed in vivo 1 h after injection. Compared to the traditional Gd3+-loaded nanoparticles for single-modal MRI, Gd-M-dots can also be radiolabeled with 64Cu2+ for positron emission tomography. Overall, these attractive properties of Gd-M-dots render them a promising imaging agent for various biomedical applications.

Targeting Phosphatidylserine with a 64Cu-Labeled Peptide for Molecular Imaging of Apoptosis.

Molecular imaging of programmed cell death (apoptosis) in vivo is an innovative strategy for early assessment of treatment response and treatment efficacy in cancer patients. Externalization of phosphatidylserine (PS) to the cell membrane surface of dying cells makes this phospholipid an attractive molecular target for the development of apoptosis imaging probes. In this study, we have radiolabeled PS-binding 14-mer peptide FNFRLKAGAKIRFG (PSBP-6) with positron-emitter copper-64 (64Cu) for PET imaging of apoptosis. Peptide PSBP-6 was conjugated with radiometal chelator 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) through an aminovaleric acid (Ava) linker for subsequent radiolabeling with 64Cu to prepare radiotracer 64Cu-NOTA-Ava-PSBP-6. PS-binding potencies of PSBP-6, NOTA-Ava-PSBP-6, and natCu-NOTA-Ava-PSBP-6 were determined in a competitive radiometric PS-binding assay. Radiotracer 64Cu-NOTA-Ava-PSBP-6 was studied in camptothecin-induced apoptotic EL4 mouse lymphoma cells and in a murine EL4 tumor model of apoptosis using dynamic PET imaging. Peptide PSBP-6 was also conjugated via an Ava linker with fluorescein isothiocyanate (FITC). FITC-Ava-PSBP-6 was evaluated in flow cytometry and fluorescence confocal microscopy experiments. Radiopeptide 64Cu-NOTA-Ava-PSBP-6 was synthesized in high radiochemical yields of >95%. The IC50 values for PS-binding potency of PSBP-6, NOTA-Ava-PSBP-6, and natCu-NOTA-PSBP-6 were 600 µM, 30 µM, and 23 µM, respectively. A competitive radiometric cell binding assay confirmed binding of 64Cu-NOTA-Ava-PSBP-6 to camptothecin-induced apoptotic EL4 cells in a Ca2+-independent manner. PET imaging studies demonstrated significantly higher uptake of 64Cu-NOTA-Ava-PSBP-6 in apoptotic EL4 tumors (SUV5min 0.95 ± 0.04) compared to control tumors (SUV5min 0.74 ± 0.03). Flow cytometry studies showed significantly higher binding of FITC-Ava-PSBP-6 to EL4 cells treated with camptothecin compared to untreated cells. Fluorescence microscopy studies revealed that FITC-Ava-PSBP-6 was binding to cell membranes of early apoptotic cells, but was internalized in late apoptotic and necrotic cells. The present study showed that radiotracer 64Cu-NOTA-Ava-PSBP-6 holds promise as a first peptide-based PET imaging agent for molecular imaging of apoptosis. However, additional "fine-tuning" of 64Cu-NOTA-Ava-PSBP-6 is required to enhance PS-binding potency and in vivo stability to improve tumor uptake and retention.

Visualization and Quantitative Assessment of the Brain Distribution of Insulin through Nose-to-Brain Delivery Based on the Cell-Penetrating Peptide Noncovalent Strategy.

Our recent work suggested that intranasal coadministration with the cell-penetrating peptide (CPP) penetratin increased the brain distribution of the peptide drug insulin. The present study aimed to distinctly certify the ability of penetratin to facilitate the nose-to-brain delivery of insulin by quantitatively evaluating the distribution characteristics in brain using radioactive (64)Cu-NODAGA-insulin. Autoradiography and analysis using a gamma counter of brain areas demonstrated that the accumulation of radioactivity was greatest in the olfactory bulb, the anterior part of the brain closest to the administration site, at 15 min after intranasal administration of (64)Cu-NODAGA-insulin with l- or d-penetratin. The brain accumulation of (64)Cu-NODAGA-insulin with penetratin was confirmed by ELISA using unlabeled insulin in which intact insulin was delivered to the brain after intranasal coadministration with l- or d-penetratin. By contrast, quantification of cerebrospinal fluid (CSF) samples showed increased insulin concentration in only the anterior portion of the CSF at 15 min after intranasal coadministration with l-penetratin. This study gives the first concrete proof that penetratin can accelerate the direct transport of insulin from the nasal cavity to the brain parenchyma. Further optimization of intranasal administration with CPP may increase the efficacy of delivery of biopharmaceuticals to the brain while reducing the risk of systemic drug exposure.

64Cu2+ Ions as PET Probe: An Emerging Paradigm in Molecular Imaging of Cancer.

Positron emission tomography (PET) imaging has transformed diagnostic nuclear medicine and become an essential strategy in cancer management. With the expected growth of this molecular imaging modality, there is a recognized need for new PET probes to address the clinical challenges in the early diagnosis and staging of various types of cancers. In this endeavor, the prospect of using 64Cu in the form of simple Cu2+ ions as PET probe is not only a cost-effective proposition but also seems poised to broaden the palette of molecular imaging probes in the foreseeable future. The usefulness of 64Cu2+ ions as PET probe is based on the fact that Cu is an essential element that plays an important role in cell proliferation and angiogenesis. Over the past few years, there has been continuous flow of evidences based on studies in animal models on the uptake of 64Cu2+ ions in different types of tumors, including, hepatoma, colorectal cancer, prostate cancer, lung cancer, breast cancer, head and neck cancer, fibrosarcoma, melanoma, glioblastoma, and ovarian cancer. The widespread preclinical success of 64Cu2+ ions as PET probe has recently resulted in translation of this radiotracer to clinical settings for noninvasive imaging and staging of prostate cancer in human patients. In this concise review, we have focused on the latest developments in PET imaging of cancer in preclinical and clinical settings using 64Cu2+ ion as a probe and discussed the challenges and opportunities for future development.

Positron emission tomography based analysis of long-circulating cross-linked triblock polymeric micelles in a U87MG mouse xenograft model and comparison of DOTA and CB-TE2A as chelators of copper-64.

Copolymers of ABC-type (PEG-PHEMA-PCMA) architecture were prepared by atom transfer radical polymerization and formulated as micelles with functionalizable primary alcohols in the shell-region (PHEMA-block) to which the metal-ion chelators DOTA or CB-TE2A were conjugated. Using this micelle system we compared the in vivo stabilities of DOTA and CB-TE2A as chelators of (64)Cu in micelle nanoparticles. The coumarin polymer (PCMA-block) micelle core was cross-linked by UV irradiation at 2 W/cm(2) for 30 min. The cross-linked micelles were labeled with (64)Cu at room temperature for 2 h (DOTA) or 80 °C for 3 h (CB-TE2A), giving labeling efficiencies of 60-76% (DOTA) and 40-47% (CB-TE2A). (64)Cu-micelles were injected into tumor-bearing mice (8 mg/kg) and PET/CT scans were carried out at 1, 22, and 46 h postinjection. The micelles showed good blood stability (T1/2: 20-26 h) and tumor uptake that was comparable with other nanoparticle systems. The DOTA micelles showed a biodistribution similar to the CB-TE2A micelles and the tumor uptake was comparable for both micelle types at 1 h (1.9% ID/g) and 22 h (3.9% ID/g) but diverged at 46 h with 3.6% ID/g (DOTA) and 4.9% ID/g (CB-TE2A). On the basis of our data, we conclude that cross-linked PEG-PHEMA-PCMA micelles have long circulating properties resulting in tumor accumulation and that DOTA and CB-TE2A (64)Cu-chelates show similar in vivo stability for the studied micelle system.

Evaluation of production cross-sections for theranostic 67Cu radionuclide via proton-induced nuclear reaction on 68Zn target.

Copper-67 (T1/2 = 61.83 h, Eß-mean=141 keV, Iß-total=100%; Eγ = 184.577 keV, Iγ = 48.7%) is a promising radionuclide for theranostic applications especially in radio immunotherapy. However, one of the main drawbacks for its application is related to its limited availability. Various nuclear reaction routes investigated in the last years can result in 67Cu production, although the use of proton beams is the method of choice taken into account in this work. The goal of this work is a revision of the cross-sections aimed at 67Cu yield, which were evaluated for the 68Zn(p,2p)67Cu reaction route up to 80 MeV proton energy. A well-defined statistical procedure, i.e., the Simultaneous Evaluation on KALMAN (SOK), combined with the least-squares concept, was used to obtain the evaluated data together with the covariance matrix. The obtained evaluated data were also compared to predictions provided by the nuclear reaction model codes TALYS and EMPIRE, and a partial agreement among them has been found. These data may be useful for both existing and potential applications in nuclear medicine, to achieve an improvement and validation of the various nuclear reaction models, and may also find applications in other fields (e.g., activation analysis and thin layer activation).

[Analysis of radioactivation induced by high-energy X-rays in medical linear accelerators -estimation of short-lived radioactivated nuclides-].

In medical linear accelerators, radioactivation is induced on the target and neighborhood parts by photoneutrons accompanying a photo-nuclear reaction and leading to higher acceleration energy. We measured the residual radiation from the radioactivated materials according to the time, and tried to identify radioactivated nuclides and their relative quantities by means of measurement results. It was presumed that the main source of residual radiations was the Target, Flattening filter and Primary collimator in the linac head. Among those materials (copper, tungsten), we calculated decrement curves of residual radiations from radioactivated nuclides generated with photo-nuclear reaction or thermal neutron capture reaction by various ratios, and we investigated the ratio that best fit the measured data. Consequently, it was presumed that (66)Cu generated with thermal neutron capture reaction contributed the most to residual radiation, followed by (62)Cu generated with photo-nuclear reaction contributed. It is important to understand various characteristics of these nuclides and to undertake management of the device.

Rapid dissemination of Francisella tularensis and the effect of route of infection.

BACKGROUND: Francisella tularensis subsp. tularensis is classified as a Category A bioweapon that is capable of establishing a lethal infection in humans upon inhalation of very few organisms. However, the virulence mechanisms of this organism are not well characterized. Francisella tularensis subsp. novicida, which is an equally virulent subspecies in mice, was used in concert with a microPET scanner to better understand its temporal dissemination in vivo upon intranasal infection and how such dissemination compares with other routes of infection. Adult mice were inoculated intranasally with F. tularensis subsp. novicida radiolabeled with 64Cu and imaged by microPET at 0.25, 2 and 20 hours post-infection. RESULTS: 64Cu labeled F. tularensis subsp. novicida administered intranasally or intratracheally were visualized in the respiratory tract and stomach at 0.25 hours post infection. By 20 hours, there was significant tropism to the lung compared with other tissues. In contrast, the images of radiolabeled F. tularensis subsp. novicida when administered intragastrically, intradermally, intraperitoneally and intravenouslly were more generally limited to the gastrointestinal system, site of inoculation, liver and spleen respectively. MicroPET images correlated with the biodistribution of isotope and bacterial burdens in analyzed tissues. CONCLUSION: Our findings suggest that Francisella has a differential tissue tropism depending on the route of entry and that the virulence of Francisella by the pulmonary route is associated with a rapid bacteremia and an early preferential tropism to the lung. In addition, the use of the microPET device allowed us to identify the cecum as a novel site of colonization of Francisella tularensis subsp. novicida in mice.

Metallome evolution in ageing C. elegans and a copper stable isotope perspective.

Ageing is accompanied by important chemical deregulations resulting in bodily metal imbalances. The way and extent to which these deregulations are associated with ageing processes are however poorly understood and their use as potential biomarkers of ageing has not been investigated. In this study, we report whole-body elementary concentrations and copper and zinc isotopic compositions of Caenorhabditis elegans in ageing wild type (i.e.'normal'-lived) and mutant (i.e. short and long-lived) strains. We show that the strains are characterized by different levels of mutation-related variations such as in phosphorus and magnesium as well as in zinc isotopic composition. During ageing, strains are affected by elemental age-related variations, such as an increase in calcium and iron concentrations and a decrease in the copper isotopic composition and concentration for long-lived mutants. The deregulated metabolism of copper seems to be connected to ageing probably in association with the production of reactive oxygen species. We emphasize that the copper stable isotope composition could serve as a biomarker of normal or accelerated ageing in the future.

Tracing Copper Migration in the Tongling Area through Copper Isotope Values in Soils and Waters.

Copper mining in Tongling has occurred since the Bronze Age, and this area is known as one of the first historic places where copper has been, and is currently, extracted. Multiple studies have demonstrated, through concentrated work on soils and waters, the impact of mining in the area. Here we present copper isotope values of 13 ore samples, three tailing samples, 20 water samples (surface and groundwater), and 94 soil samples (15 different profiles ranging in depth from 0⁻2 m) from proximal to distal (up to 10 km) locations radiating from a tailings dam and tailings pile. Oxidation of the copper sulfide minerals results in isotopically heavier oxidized copper. Thus, copper sourced from sulfide minerals has been used to trace copper in mining and environmental applications. At Tongling, higher copper isotope values (greater than 1 per mil, which are interpreted to be derived from copper sulfide weathering) are found both in waters and the upper portions of soils (5⁻100 cm) within 1 km of the source tailings. At greater than 1 km, the soils do not possess heavier copper isotope values; however, the stream water samples that have low copper concentrations have heavier values up to 6.5 km from the source. The data suggest that copper derived from the mining activities remains relatively proximal in the soils but can be traced in the waters at greater distances.

RAGE-specific single chain Fv for PET imaging of pancreatic cancer.

Noninvasive detection of both early pancreatic neoplasia and metastases could enhance strategies to improve patient survival in this disease that is notorious for an extremely poor prognosis. There are almost no identifiable targets for non-invasive diagnosis by positron emission tomography (PET) for patients with pancreatic ductal adenocarcinoma (PDAC). Over-expression of the receptor for advanced glycation end products (RAGE) is found on the cell surface of both pre-neoplastic lesions and invasive PDAC. Here, a RAGE-specific single chain (scFv) was developed, specific for PET imaging in syngeneic mouse models of PDAC. An anti-RAGE scFv conjugated with a sulfo-Cy5 fluorescence molecule showed high affinity and selectivity for RAGE expressing pancreatic tumor cells and genetically engineered KRASG12D mouse models of PDAC. An in vivo biodistribution study was performed with the 64Cu-radiolabled scFv in a syngeneic murine pancreatic cancer model, demonstrating both the feasibility and potential of an anti-RAGE scFv for detection of PDAC. These studies hold great promise for translation into the clinic.

Monte Carlo N-Particle (MCNP) Modeling of the Cellular Dosimetry of 64Cu: Comparison with MIRDcell S Values and Implications for Studies of Its Cytotoxic Effects.

64Cu emits positrons as well as ß- particles and Auger and internal conversion electrons useful for radiotherapy. Our objective was to model the cellular dosimetry of 64Cu under different geometries commonly used to study the cytotoxic effects of 64Cu. METHODS: Monte Carlo N-Particle (MCNP) was used to simulate the transport of all particles emitted by 64Cu from the cell surface (CS), cytoplasm (Cy), or nucleus (N) of a single cell; monolayer in a well (radius = 0.32-1.74 cm); or a sphere (radius = 50-6,000 µm) of cells to calculate S values. The radius of the cell and N ranged from 5 to 12 µm and 2 to 11 µm, respectively. S values were obtained by MIRDcell for comparison. MCF7/HER2-18 cells were exposed in vitro to 64Cu-labeled trastuzumab. The subcellular distribution of 64Cu was measured by cell fractionation. The surviving fraction was determined in a clonogenic assay. RESULTS: The relative differences of MCNP versus MIRDcell self-dose S values (Sself) for 64Cu ranged from -0.2% to 3.6% for N to N (SN←N), 2.3% to 8.6% for Cy to N (SN←Cy), and -12.0% to 7.3% for CS to N (SN←CS). The relative differences of MCNP versus MIRDcell cross-dose S values were 25.8%-30.6% for a monolayer and 30%-34% for a sphere, respectively. The ratios of SN←N versus SN←Cy and SN←Cy versus SN←CS decreased with increasing ratio of the N of the cell versus radius of the cell and the size of the monolayer or sphere. The surviving fraction of MCF7 /: HER2-18 cells treated with 64Cu-labeled trastuzumab (0.016-0.368 MBq/µg, 67 nM) for 18 h versus the absorbed dose followed a linear survival curve with α = 0.51 ± 0.05 Gy-1 and R2 = 0.8838. This is significantly different from the linear quadratic survival curve of MCF7 /: HER2-18 cells exposed to γ-rays. CONCLUSION: MCNP- and MIRDcell-calculated S values agreed well. 64Cu in the N increases the dose to the N in isolated single cells but has less effect in a cell monolayer or small cluster of cells simulating a micrometastasis, and little effect in a sphere analogous to a tumor xenograft compared with 64Cu in the Cy or on the CS. The dose deposited by 64Cu is less effective for cell killing than γ-rays.

Exploiting Kalman Filtering Non-linear Exponential Fitting to Promote the Energy Resolution of 137Cs and 60Co Gamma Ray Spectra.

For Cs and Co gamma ray spectra, gamma ray energy is proportional to the amplitude of the pulse signal, and energy resolution can be improved by pulse signal processing with mathematical algorithms. Influenced by system measurement noise and baseline fluctuation, the pulse amplitude is difficult to calculate accurately. A method that combines the Kalman filter baseline estimation with the non-linear exponential fitting has been used. By this method, the pulse signal is divided into two parts: one is the raising edge before the pulse peak, and another is after the pulse peak. The pulse amplitude equals the difference between the pulse starting height and the pulse peak height. The pulse starting height is obtained by Kalman filter baseline estimation on the rising edge of the pulse starting point. The pulse peak height is calculated by nonlinear exponential fitting on the falling edge of the pulse highest point. When the sampling rate is 100 MHz, the pulse signals obtained from a Cd(Zn)Te detector are analyzed by this method. Results have shown that the processed pulses have a more distinguishable amplitude distribution; energy resolution for the Cs spectrum is approximately 2.97% at 662 keV (~19.66 keV FWHM), and for the Co spectrum it is 2.61% at 1,332 keV (~34.76 keV FWHM).

Longitudinal assessment of metal concentrations and copper isotope ratios in the G93A SOD1 mouse model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease, which involves progressive motor neuron degeneration in the central nervous system (CNS). The G93A SOD1 mouse model simulates one of the most common causes of familial ALS through the overexpression of a mutated form of the human gene encoding copper/zinc superoxide dismutase (SOD1). Transition metals, particularly Cu and Zn, have been shown to behave abnormally in the disease context and have been hypothesized to contribute to and potentially trigger the disease. In this study, concentrations of Cu, Zn and Fe, as well as Cu isotope ratios were assessed in keystone tissues of ALS, including the brain, spinal cord, muscle and whole blood, from transgenic mutant SOD1G93A mice and non-transgenic controls. While no consistent Cu isotope signal was found to be related to the disease state, concentrations of Cu, Zn and Fe were significantly elevated in muscle tissue of the transgenic mice, even at pre-symptomatic time points. In brain and muscle tissue, in both animal groups, a time-dependent Cu isotope signal was observed. We hypothesize that the early and significant elevation in metal concentration in muscle tissue from SOD1 transgenic mice could facilitate the development of ALS, without affecting the overall signal from well-buffered CNS tissues. Ageing may be recorded isotopically as a shift from a neonatal Cu pool as inherited from the mother, through dietary Cu and recycling processes.

Preparation of [61Cu]-2-acetylpyridine thiosemicarbazone complex as a possible PET tracer for malignancies.

Due to the interesting anti-proliferative properties of copper-thiosemicarbazone complexes, the production of a (61)Cu-labeled thiosemicarbazone, i.e. 2-acetylpyridine thiosemicarbazone (APTS) was investigated. Copper-61 (T(1/2)=3.33 h) was produced via the (64)Zn(p,alpha)(61)Cu nuclear reaction using a natural zinc target irradiated with 22 MeV protons for 500 microAh. The (61)Cu was separated from the irradiated target material by a two-step method and converted to acetate; this yielded a final activity of 222 GBq (6.0 Ci), with a radiochemical yield of >95%. The (61)Cu-acetate was mixed with 2-acetylpyridine thiosemicarbazone for 30 min at room temperature to yield [(61)Cu]APTS with a radiochemical yield of more than 80%. Colorimetric methods showed that residual chemical impurities in the product were below the accepted limits. Radio thin layer chromatography (RTLC) showed a radiochemical purity of more than 99% after C(18) column chromatography. A specific activity of about 370-740 MBq/mmol (10-20 Ci/mmol) was obtained. The stability of the final product was checked in the absence and presence of human serum at 37 degrees C for up to 3 h. The partition coefficient of the final complex was also determined.

Imaging of Brain Tumors with Copper-64 Chloride: Early Experience and Results.

OBJECTIVES: To conduct the first investigational study that is aimed at evaluating the ability of the simple salt (64)CuCl2 to diagnose cerebral tumors in patients affected by glioblastoma multiforme (GBM). METHODS: Nineteen patients with a documented history and radiologic evidence of brain tumors were enrolled in the study. Eighteen patients were diagnosed with GBM, and one patient was diagnosed with grade II astrocytoma. After initial cerebral magnetic resonance imaging (MRI), patients were administered with (64)CuCl2 (13 MBq/kg) and brain positron emission tomography (PET)/computed tomography (CT) imaging was performed at 1, 3, and 24 hours after administration. Standardized uptake values (SUVs) were calculated and used to figure out the pharmacokinetic profile of the tracer. Absorbed radiation doses were estimated using OLINDA/EXM. RESULTS: Copper-64 chloride clearly visualized brain cancerous lesions within 1 hour after injection, with stable retention of radioactivity at 3 and 24 hours. Excellent agreement was found between PET/CT and MRI. No uptake of the tracer was observed in low-grade astrocytoma. The agent cleared rapidly from the blood and was mostly excreted through the liver, without significant kidney washout. Analysis of time variation of SUVmax values showed persistent uptake in malignant tissues with a slight increase of radioactive concentration at 24 hours. CONCLUSIONS: Copper-64 chloride has favorable biological properties for brain imaging and warrants further investigation as a diagnostic tracer for GBM.

Calibration setting numbers for dose calibrators for the PET isotopes (52)Mn, (64)Cu, (76)Br, (86)Y, (89)Zr, (124)I.

For PET radionuclides, the radioactivity of a sample can be conveniently measured by a dose calibrator. These devices depend on a "calibration setting number", but many recommended settings from manuals were interpolated based on standard sources of other radionuclide(s). We conducted HPGe gamma-ray spectroscopy, resulting in a reference for determining settings in two types of vessels containing one of several PET radionuclides. Our results reiterate the notion that in-house, experimental calibrations are recommended for different radionuclides and vessels.