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Imaging capabilities of the Inveon SPECT system using single-and multipinhole collimators
No full textThe Inveon small-animal SPECT system comes with several types of multipinhole collimator plates. We evaluate here the performance measurements of the Inveon SPECT system using 6 different collimators: 3 dedicated for mouse imaging and 3 for rat imaging. Methods: The measured performance parameters include the sensitivity, the spatial resolution using line sources, the ultra-micro Derenzo phantom, the recovery coefficient and the noise measurements using the National Electrical Manufacturers Association NU-4 image quality phantom, obtained with the 2 reconstruction algorithms available with the Inveon Acquisition Workplace, version 1.5—the 3-dimensional ordered-subset expectation maximization (3DOSEM) and the 3-dimensional maximum a posteriori (3DMAP). Further, the overall performance of the system is illustrated by an animal experiment. Results: The results show that the Inveon SPECT scanner offers a spatial resolution, measured at the center of the field of view, ranging from 0.6 to 1 mm with the collimator plates dedicated to mouse imaging and from 1.2 to less than 2 mm with rat collimator plates. The system sensitivity varies from 29 to 404 cps/MBq for mouse collimators and from 53 to 175 cps/MBq for rat collimators. The image quality study showed that 3DMAP allows better noise reduction while preserving the recovery coefficient, compared with other regularization strategies such as the premature termination of the 3DOSEM reconstruction or 3DOSEM followed by gaussian filtering. Conclusion: The acquisition parameters, such as the collimator set and the radius of rotation, offer a wide range of possibilities to apply to a large number of biologic studies. However, special care must be taken because this increase in sensitivity can be offset by image degradation, such as image artifacts caused by projection overlap and statistical noise due to a higher number of iterations required for convergence. 3DMAP allowed better noise reduction while maintaining relatively constant recovery coefficients, as compared with other reconstruction strategies. © 2013 by the Society of Nuclear Medicine and Molecular Imaging, Inc
Structural and magnetic properties of the ruthenium double perovskites Ba2−xSrxYRuO6
No full textThe crystal structures of the series of ordered double perovskites Ba2−xSrxYRuO6 (0 ≤ x ≤ 2) were studied by high resolution synchrotron X-ray diffraction. The materials displayed a sequence of structures image file: c4dt03682d-t1.tif associated with increasing tilting of the corner sharing octahedra. The same sequence of structures can be induced by varying the temperature of appropriate members of the series. Magnetic susceptibility measurements demonstrate the oxides to be antiferromagnets with a Neel temperature of ∼30 K. There is a simple correlation between the Weiss constant θ and the Ru–O–Y bond angle. The two Sr rich oxides (x = 1.8 and 2.0) display an, unusual, sharp minimum in susceptibility at low temperatures that is associated with the reorientation of the spins. © 2015 The Royal Society of Chemistr
Peptide modification of purified gellan gum
No full textAbstractGellan gum (GG) is an anionic polysaccharide with potential as a biopolymer for additive manufacturing (3D-bioprinting) and tissue engineering. Previous studies have shown GG to be highly cytocompatible, but lacking specific attachment sites required for anchorage-dependent cells. In this work, we modify purified-GG polymer with a short peptide containing the arginine-glycine-aspartic acid (RGD) sequence that is known to enhance integrin-mediated cell attachment. Radiolabelling of the peptide was used in optimisation of the conjugation procedure to achieve an overall efficiency of 40%. The purification of divalent cations from commercial GG samples was found to be critical for successful conjugation. Rheological studies revealed that the peptide coupling did not prevent gelation behaviour. C2C12 cells showed improved attachment on the surface of and encapsulated within RGD-GG hydrogels, differentiating to multinucleated myofibers after 5–7 days. PC12 cells showed minimal interactions with both GG and RGD-GG, with formation of cell clusters and impedance of terminal differentiation and neurite extension. © 2015 Royal Society of Chemistr
Synthesis and biological characterisation of 18F-SIG343 and 18F-SIG353, novel and high selectivity σ2 radiotracers, for tumour imaging properties
Get PDFSigma2 (σ2) receptors are highly expressed in cancer cell lines and in tumours. Two novel selective 18F-phthalimido σ2 ligands, 18F-SIG343 and 18F-SIG353, were prepared and characterised for their potential tumour imaging properties. © 2013 Nguyen et al.; licensee Springer.© Nguyen et al.; licensee Springer. 2013
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
The role of additives in moderating the influence of Fe(III) and Cu(II) on the radiochemical yield of [68Ga(DOTATATE)]
No full text68Ga(DOTATATE)] has demonstrated its clinical usefulness. Both Fe3+ and Cu2+, potential contaminants in Gallium-68 generator eluent, substantially reduce the radiochemical (RC) yield of [68Ga(DOTATATE)] if the metal/ligand ratio of 1:1 is exceeded. A variety of compounds were examined for their potential ability to reduce this effect. Most had no effect on RC yield. However, addition of phosphate diminished the influence of Fe3+ by likely forming an insoluble iron salt. Addition of ascorbic acid reduced Cu2+ and Fe3+ to Cu+ and Fe2+ respectively, both of which have limited impact on RC yields. At low ligand amounts (5 nmol DOTATATE), the addition of 30 nmol phosphate (0.19 mM) increased the tolerance of Fe3+ from 4 nmol to 10 nmol (0.06 mM), while the addition of ascorbic acid allowed high RC yields (>95%) in the presence of 40 nmol Fe3+ (0.25 mM) and 100 nmol Cu2+ (0.63 mM). The effect of ascorbic acid was highly pH-dependant, and gave optimal results at pH 3. © 2015 Elsevier B.V
Tunable and noncytotoxic PET/SPECT-MRI multimodality imaging probes using colloidally stable ligand-free superparamagnetic iron oxide nanoparticles
Get PDFPhysiologically stable multimodality imaging probes for positron emission tomography/single-photon emission computed tomography (PET/SPECT)-magnetic resonance imaging (MRI) were synthesized using the superparamagnetic maghemite iron oxide (γ-Fe2O3) nanoparticles (SPIONs). The SPIONs were sterically stabilized with a finely tuned mixture of diblock copolymers with either methoxypolyethylene glycol (MPEG) or primary amine NH2 end groups. The radioisotope for PET or SPECT imaging was incorporated with the SPIONs at high temperature. 57Co2+ ions with a long half-life of 270.9 days were used as a model for the radiotracer to study the kinetics of radiolabeling, characterization, and the stability of the radiolabeled SPIONs. Radioactive 67Ga3+ and Cu2+-labeled SPIONs were also produced successfully using the optimized conditions from the 57Co2+-labeling process. No free radioisotopes were detected in the aqueous phase for the radiolabeled SPIONs 1 week after dispersion in phosphate-buffered saline (PBS). All labeled SPIONs were not only well dispersed and stable under physiological conditions but also noncytotoxic in vitro. The ability to design and produce physiologically stable radiolabeled magnetic nanoparticles with a finely controlled number of functionalizable end groups on the SPIONs enables the generation of a desirable and biologically compatible multimodality PET/SPECT-MRI agent on a single T2 contrast MRI probe. © 2017 Dove Press Ltd.This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License
Detection of apoptotic cell death in the thymus of dexamethasone treated rats using [123I]Annexin V and in situ oligonucleotide ligation
No full textIn the present study we aimed to establish an animal model of dexamethasone (DEX)-induced apoptosis in the thymus of rats. The degree of apoptosis was determined in the same animals at 6 and 11 h after a single administration of DEX (5 mg/kg, ip) by (a) in vivo biodistribution of the uptake of [123I]Annexin V, a biomarker of the early stages of apoptosis; (b) in vitro evaluation of the apoptotic index (percentage of number of apoptotic cells versus total number of cells) in the form of DNA fragmentation, on tissue sections using in situ oligo ligation (ISOL). ISOL demonstrated a 62- and 90-fold increase of apoptotic index at 6 and 11 h after DEX administration respectively, in the outer part of the thymic lobule (cortex) and a 25- and 54-fold increases in the inner part of the thymic lobule (medulla) in the corresponding treatment groups. In the biodistribution study, [123I]Annexin V uptake was significantly increased in the thymus of rats 11 h after DEX administration (by 1.3- to 1.4-fold) and significantly decreased at the 6-h time point. We conclude that the specificity of the apoptotic signal provided by isotopic methods in vivo would always require confirmation by complementary in vitro techniques that verify the assessment of ongoing apoptosis accurately. © 2007 Springer Science+Business Media B.V
A high-resolution multi-proxy palaeoecological record of the last two glacial cycles from Lake Selina, Tasmania
No full textHere we present the results of a continuous high resolution multi-proxy data set spanning the last
two glacial cycles (ca 230,000 years) from Lake Selina, Tasmania. The data set includes pollen,
charcoal, geochemistry and magnetic properties. We compare and discuss ecological trends
between the Last Interglacial and the Holocene, reflecting on the role of people in radically altering
the vegetation landscape. We also present tantalising data suggesting a possible Antarctic Cold
Reversal-like shift through the penultimate Glacial Termination (T2)
Bardoxolone methyl prevents fat deposition and inflammation in brown adipose tissue and enhances sympathetic activity in mice fed a high-fat diet
Get PDFObesity results in changes in brown adipose tissue (BAT) morphology, leading to fat deposition, inflammation, and alterations in sympathetic nerve activity. Bardoxolone methyl (BARD) has been extensively studied for the treatment of chronic diseases. We present for the first time the effects of oral BARD treatment on BAT morphology and associated changes in the brainstem. Three groups (n = 7) of C57BL/6J mice were fed either a high-fat diet (HFD), a high-fat diet supplemented with BARD (HFD/BARD), or a low-fat diet (LFD) for 21 weeks. BARD was administered daily in drinking water. Interscapular BAT, and ventrolateral medulla (VLM) and dorsal vagal complex (DVC) in the brainstem, were collected for analysis by histology, immunohistochemistry and Western blot. BARD prevented fat deposition in BAT, demonstrated by the decreased accumulation of lipid droplets. When administered BARD, HFD mice had lower numbers of F4/80 and CD11c macrophages in the BAT with an increased proportion of CD206 macrophages, suggesting an anti-inflammatory effect. BARD increased phosphorylation of tyrosine hydroxylase in BAT and VLM. In the VLM, BARD increased energy expenditure proteins, including beta 3-adrenergic receptor (β3-AR) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). Overall, oral BARD prevented fat deposition and inflammation in BAT, and stimulated sympathetic nerve activity. © 2015 by the authors; licensee MDPI, Basel, SwitzerlandThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/). Copy acquired from MDPI: http://www.mdpi.com/2072-6643/7/6/4705
Hardware and software modifications on the Advion NanoTek microfluidic platform to extend flexibility for radiochemical synthesis
No full textMicrofluidic systems are currently receiving a lot of attention in the PET radiochemistry field, due to their demonstrated ability to obtain higher incorporation yields with reduced total processing time and using a decreased amount of precursors. The Advion NanoTek LF was the first commercial microfluidic system available for radiochemistry that allows basic parameter optimization to be performed. In this paper we report hardware and software modifications that would allow better performing procedures, higher product throughput and flexibility to utilize the system. In particular, HPLC purification and SPE formulation have been fully integrated. © 2014 Elsevier Ltd