Optimization of cyclotron production for radiometal of Zirconium 89

Zirconium 89 (89Zr) is a promising radionuclide for development of new PET agents due to its convenient half life of 78.4 h, β+ emission rate of 23%, low maximum energy of 0.9 MeV resulting in good spatial resolution, a stable daughter isotope of yttrium-89 (89Y) and favorable imaging characteristics, with only one significant γ-line of 909 keV emitted during decay alongside the 511 keV positron photons. Our aim was to share over 2 years of experience of producing isotopically pure 89Zr via the 89Y(p,n)89Zr nuclear reaction with a COSTIS Solid Target System (STS) and CYCLONE 18/9 cyclotron. We optimized the yields without producing either of the long-lived impurities 88Zr or 88Y. The degradation of the beam energy with 400 and 500 μm thick niobium foils was tested without overheating problems within 2-6 h of irradiation. From repeated measurements of activity, it was clear that there is a bi-exponential decay of radioactivity due to the short lived 89mZr and 89Zr. The measured half life of the longer lived radionuclide was consistent with value for 89Zr. The energy spectrum from 89Zr had energy peaks at 511 keV and 909 keV and was consistent with 89Zr. Production of 89Zr with 400 (Ep = 9.8 MeV) and 500 μ m (Ep = 11.6 MeV) thick niobium beam degrader was achieved, without producing either 88Zr or 88Y. It was necessary to wait at least 4 hours before measuring the activity and decay correct in order to calculate the 89Zr activity at the end of cyclotron production. Degrading the proton beam to 10 MeV produces radionuclidically pure 89Zr with yields from 8 to 9 MBq/μAh. Whilst this is enough for pre-clinical use, the yield is not enough for either clinical use or commercial supply. Use of thinner beam degraders (400 μm) increases the proton beam energy and increases the radionuclidic yield to 15.5 MBq/μAh whilst maintaining radionuclidic purity

Radiosynthesis of [18F]-Labelled Pro-Nucleotides (ProTides).

Phosphoramidate pro-nucleotides (ProTides) have revolutionized the field of anti-viral and anti-cancer nucleoside therapy, overcoming the major limitations of nucleoside therapies and achieving clinical and commercial success. Despite the translation of ProTide technology into the clinic, there remain unresolved in vivo pharmacokinetic and pharmacodynamic questions. Positron Emission Tomography (PET) imaging using [18F]-labelled model ProTides could directly address key mechanistic questions and predict response to ProTide therapy. Here we report the first radiochemical synthesis of [18F]ProTides as novel probes for PET imaging. As a proof of concept, two chemically distinct radiolabelled ProTides have been synthesized as models of 3'- and 2'-fluorinated ProTides following different radiosynthetic approaches. The 3'-[18F]FLT ProTide was obtained via a late stage [18F]fluorination in radiochemical yields (RCY) of 15-30% (n = 5, decay-corrected from end of bombardment (EoB)), with high radiochemical purities (97%) and molar activities of 56 GBq/μmol (total synthesis time of 130 min.). The 2'-[18F]FIAU ProTide was obtained via an early stage [18F]fluorination approach with an RCY of 1-5% (n = 7, decay-corrected from EoB), with high radiochemical purities (98%) and molar activities of 53 GBq/μmol (total synthesis time of 240 min)

Listen up! Listening skills in accounting education : gaps and proposed new research and teaching agendas

Utilising a systematic literature review, this paper synthesises alternative theoretical perspectives on listening and studies of accounting students’ listening skills. It identifies gaps in the conceptualisation of listening within accounting education research. Research and teaching agendas are then developed which provide a framework for more effectively fostering the development of listening skills in accounting education. We identify the need for research and teaching around: why listening matters; the elements of effective listening; and developing listening skills. Greater focus on the interpersonal, social, and reflexive aspects of listening is needed, going beyond an existing focus on comprehension and information acquisition. There is also a need to explicitly address the role and benefits of listening in facilitating an ethical organisational culture, recognising the ethical dimensions of professional responsibility and active listening as part of empathetic leadership

Listen up! Listening skills in accounting education: gaps and proposed new research and teaching agendas

Utilising a systematic literature review, this paper synthesises alternative theoretical perspectives on listening and studies of accounting students’ listening skills. It identifies gaps in the conceptualisation of listening within accounting education research. Research and teaching agendas are then developed which provide a framework for more effectively fostering the development of listening skills in accounting education. We identify the need for research and teaching around: why listening matters; the elements of effective listening; and developing listening skills. Greater focus on the interpersonal, social, and reflexive aspects of listening is needed, going beyond an existing focus on comprehension and information acquisition. There is also a need to explicitly address the role and benefits of listening in facilitating an ethical organisational culture, recognising the ethical dimensions of professional responsibility and active listening as part of empathetic leadership

A self organizing map for exploratory analysis of PET radiomic features

Texture analysis for quantification of intratumor uptake heterogeneity in PET/CT images has received increasing attention. This allows the extraction of a large number of ‘radiomic’ features to be correlated with end point information such as tumor type, therapy response, prognosis. The conventional complex workflow for calculation of texture features introduces numerous confounding variables. This non exhaustively includes, imaging time post administration of radiopharmaceutical and the method and extent of functional volume segmentation. A lack of understanding on the dependency of texture features with these variables serves as a detriment to the urgent need to standardize texture measurements to pool results from different imaging centers. The utilization of machine learning techniques for feature (and their combinations) selection serves as a promising method to alleviate redundancy in radiomics. To this avail, we introduce for the first time the application of a Kohonen self-organizing feature map to identify the emergent properties present when performing texture analysis. The application of the self-organizing map to radiomic analysis serves as a powerful general-purpose exploratory instrument to reveal the statistical indicators of texture distributions. For this purpose, texture features from PET-CT images of 8 pre-clinical mice with mammary carcinoma xenografts were analyzed with varying post injection imaging time and tumor segmentation contour size. This varying distribution of texture parameters were interpreted by the self-organizing map to reveal two distinct clusters of texture features which are dependent on contour size, providing additional evidence that contour size and hence segmentation method is a confounding variable when performing texture analysis. Furthermore, the self-organizing map can be utilized as a method to incorporate this revealed dependency in a prediction model in the presence of end point information, which will be an area of future work

The CF-Sputum Induction Trial (CF-SpIT) to assess lower airway bacterial sampling in young children with cystic fibrosis: a prospective internally controlled interventional trial

Background Pathogen surveillance is challenging but crucial in children with cystic fibrosis—who are often nonproductive of sputum even if actively coughing—because infection and lung disease begin early in life. The role of sputum induction as a diagnostic tool for infection has not previously been systematically addressed in young children with cystic fibrosis. We aimed to assess the pathogen yield from sputum induction compared with that from cough swab and single-lobe, two-lobe, and six-lobe bronchoalveolar lavage. Methods This prospective internally controlled interventional trial was done at the Children’s Hospital for Wales (Cardiff, UK) in children with cystic fibrosis aged between 6 months and 18 years. Samples from cough swab, sputum induction, and single-lobe, two-lobe, and six-lobe bronchoalveolar lavage were matched for within-patient comparisons. Primary outcomes were comparative pathogen yield between sputum induction and cough swab for stage 1, and between sputum induction, and single-lobe, two-lobe, and six-lobe bronchoalveolar lavage for stage 2. Data were analysed as per protocol. This study is registered with the UK Clinical Research Network (14615) and with the International Standard Randomised Controlled Trial Network Registry (12473810). Findings Between Jan 23, 2012, and July 4, 2017, 124 patients were prospectively recruited to the trial and had 200 sputum induction procedures for stage 1. 167 (84%) procedures were successful and the procedure was well tolerated. Of the 167 paired samples, 63 (38%) sputum-induction samples were pathogen positive compared with 24 (14%) cough swabs (p<0·0001; odds ratio [OR] 7·5; 95% CI 3·19–17·98). More pathogens were isolated from sputum induction than cough swab (79 [92%] of 86 vs 27 [31%] of 86; p<0·0001). For stage 2, 35 patients had a total of 41 paired sputum-induction and bronchoalveolar lavage procedures. Of the 41 paired samples, 28 (68%) were positive for at least one of the concurrent samples. 39 pathogens were isolated. Sputum induction identified 27 (69%) of the 39 pathogens, compared with 22 (56%; p=0·092; OR 3·3, 95% CI 0·91–12·11) on single-lobe, 28 (72%; p=1·0; OR 1·1, 95% CI 0·41–3·15) on two-lobe, and 33 (85%; p=0·21; OR 2·2, 95% CI 0·76–6·33) on six-lobe bronchoalveolar lavage. Interpretation Sputum induction is superior to cough swab for pathogen detection, is effective at sampling the lower airway, and is a credible surrogate for bronchoalveolar lavage in symptomatic children. A substantial number of bronchoscopies could be avoided if sputum induction is done first and pathogens are appropriately treated. Both sputum induction and six-lobe bronchoalveolar lavage provide independent, sizeable gains in pathogen detection compared with the current gold-standard two-lobe bronchoalveolar lavage. We propose that sputum induction and six-lobe bronchoalveolar lavage combined are used as standard of care for comprehensive lower airway pathogen detection in children with cystic fibrosis

Discovery and Biosynthesis of Gladiolin: A Burkholderia gladioli Antibiotic with Promising Activity against Mycobacterium tuberculosis.

An antimicrobial activity screen of Burkholderia gladioli BCC0238, a clinical isolate from a cystic fibrosis patient, led to the discovery of gladiolin, a novel macrolide antibiotic with potent activity against Mycobacterium tuberculosis H37Rv. Gladiolin is structurally related to etnangien, a highly unstable antibiotic from Sorangium cellulosum that is also active against Mycobacteria. Like etnangien, gladiolin was found to inhibit RNA polymerase, a validated drug target in M. tuberculosis. However, gladiolin lacks the highly labile hexaene moiety of etnangien and was thus found to possess significantly increased chemical stability. Moreover, gladiolin displayed low mammalian cytotoxicity and good activity against several M. tuberculosis clinical isolates, including four that are resistant to isoniazid and one that is resistant to both isoniazid and rifampicin. Overall, these data suggest that gladiolin may represent a useful starting point for the development of novel drugs to tackle multidrug-resistant tuberculosis. The B. gladioli BCC0238 genome was sequenced using Single Molecule Real Time (SMRT) technology. This resulted in four contiguous sequences: two large circular chromosomes and two smaller putative plasmids. Analysis of the chromosome sequences identified 49 putative specialized metabolite biosynthetic gene clusters. One such gene cluster, located on the smaller of the two chromosomes, encodes a trans-acyltransferase (trans-AT) polyketide synthase (PKS) multienzyme that was hypothesized to assemble gladiolin. Insertional inactivation of a gene in this cluster encoding one of the PKS subunits abrogated gladiolin production, confirming that the gene cluster is responsible for biosynthesis of the antibiotic. Comparison of the PKSs responsible for the assembly of gladiolin and etnangien showed that they possess a remarkably similar architecture, obfuscating the biosynthetic mechanisms responsible for most of the structural differences between the two metabolites

L-selectin enhanced T cells improve the efficacy of cancer immunotherapy

The T cell homing molecule, L-selectin (CD62L), is commonly used as a marker of T cell activation, as expression of L-selectin is downregulated following engagement of the T cell receptor. Furthermore, it is used to distinguish “central memory” T cells (TCM) from, “effector memory” T cells (TEM). It has been reported that CD8+ T cells with a CD62L+ TCM phenotype are better able to control tumour growth than CD62L- TEM CD8+ T cells, while L-selectin knockout T cells are poor at controlling tumour growth. Here, we test the hypothesis that T cells expressing a genetically modified form of L-selectin that is not downregulated following T cell activation (L-selectin enhanced T cells) are better able to control tumour growth than wild type T cells. Using mouse models of solid and disseminated tumours, we show that L-selectin enhancement improves the efficacy of CD8+ T cells in controlling tumour growth. Longitudinal tracking of Zirconium-89 (89Zr) labelled T cells using PET-CT showed that transferred T cells localised to tumours within 24 hours. Early T cell recruitment into tumours was not dependent on L-selectin, however, upregulation of the early activation marker CD69 was higher on L-selectin expressing T cells both inside tumours and in secondary lymphoid organs. Reduced growth of tumours by L-selectin enhanced T cells correlated with increased frequency of CD8+ tumour infiltrating T cells 21 days after commencing therapy. Ex vivo analysis showed that clonal expansion of L-selectin enhanced T cells was slower, and that L-selectin was linked to expression of the proliferation marker Ki67. Together these findings indicate that maintaining L-selectin expression on tumour-specific T cells offers an advantage in mouse models of cancer immunotherapy. The beneficial role of L-selectin may be unrelated to its’ well-known role in T cell homing and instead linked to activation, clonal expansion and retention of therapeutic T cells. These findings have implications both for the selection of T cell subsets for adoptive transfer immunotherapy, and for possible modifications of transgenic chimeric antigen receptor (CAR) T cells to broaden the clinical scope of these therapies