Using Covalent Modifications to Distinguish Protein Electrospray Mechanisms: Charged Residue Model (CRM) vs. Chain Ejection Model (CEM)

Different mechanisms have been proposed for the formation of gaseous protein ions during electrospray ionization (ESI). In the charged residue model (CRM) ions are produced upon nanodroplet evaporation to dryness. This mechanism is thought to dominate in native ESI, where proteins retain compact conformations, with charge states close to the Rayleigh charge of protein-sized aqueous droplets. Much higher charge states are generated from proteins that are unfolded in solution. The chain ejection model (CEM) has been proposed for ESI under such denaturing conditions. In the CEM proteins are gradually expelled, while mobile H+ equilibrate between the droplet and its protruding tail. Providing clear-cut evidence for these scenarios remains difficult, because electrosprayed ions do not usually retain any features that reveal their formation mechanism. In this work we propose that the stepwise elimination of basic sites can serve to distinguish between the CRM and CEM. Using cytochrome c as a model system, we studied proteins that had between zero and 19 Lys blocked by acetylation. In native ESI (pH 7) the same low charge states were observed regardless of acetylation. This behavior is consistent with the CRM, where charge states are governed by protein size, rather than protein surface chemistry. Denaturing (pH 2) conditions resulted in much higher ESI charge states. Intriguingly, spectra acquired under these pH 2 conditions gradually shifted to lower charge states when the number of acetylated Lys was increased. This charge reduction is attributed to the fact that lowering the number of basic sites compromises the ability of the protein to compete with the droplet for mobile H+ during the CEM. In conclusion, we illustrate that simple covalent modifications can help distinguish between protein ion formation via the CRM or the CEM

Positron detection in silica monoliths for miniaturised quality control of PET radiotracers

We demonstrate the use of the miniaturised Medipix positron sensor for detection of the clinical PET radiotracer, [⁶⁸Ga]gallium-citrate, on a silica-based monolith, towards microfluidic quality control. The system achieved a far superior signal-to-noise ratio compared to conventional sodium iodide-based radio-HPLC detection and allowed real-time visualisation of positrons in the monolith

Network traffic analysis for threats detection in the Internet of Things

As the prevalence of the Internet of Things (IoT) continues to increase, cyber criminals are quick to exploit the security gaps that many devices are inherently designed with. Users cannot be expected to tackle this threat alone, and many current solutions available for network monitoring are simply not accessible or can be difficult to implement for the average user, which is a gap that needs to be addressed. This article presents an effective signature-based solution to monitor, analyze, and detect potentially malicious traffic for IoT ecosystems in the typical home network environment by utilizing passive network sniffing techniques and a cloud application to monitor anomalous activity. The proposed solution focuses on two attack and propagation vectors leveraged by the infamous Mirai botnet, namely DNS and Telnet. Experimental evaluation demonstrates the proposed solution can detect 98.35 percent of malicious DNS traffic and 99.33 percent of Telnet traffic for an overall detection accuracy of 98.84 percent

Inhibition of Poly(ADP-Ribose) polymerase enhances the toxicity of 131I-Metaiodobenzylguanidine/Topotecan combination therapy to cells and xenografts that express the noradrenaline transporter

Targeted radiotherapy using [131I]meta-iodobenzylguanidine ([131I]MIBG) has produced remissions in some neuroblastoma patients. We previously reported that combining [131I]MIBG with the topoisomerase I (Topo-I) inhibitor topotecan induced long-term DNA damage and supra-additive toxicity to NAT-expressing cells and xenografts. This combination treatment is undergoing clinical evaluation. This present study investigated the potential of PARP-1 inhibition, in vitro and in vivo, to further enhance [131I]MIBG/topotecan efficacy

A novel 18F-labelled high affinity agent for PET imaging of the translocator protein

The translocator protein (TSPO) is an important target for imaging focal neuroinflammation in diseases such as brain cancer, stroke and neurodegeneration, but current tracers for non-invasive imaging of TSPO have important limitations. We present the synthesis and evaluation of a novel 3-fluoromethylquinoline-2-carboxamide, AB5186, which was prepared in eight steps using a one-pot two component indium(III)-catalysed reaction for the rapid and efficient assembly of the 4-phenylquinoline core. Biological assessment and the implementation of a physicochemical study showed AB5186 to have low nanomolar affinity for TSPO, as well as optimal plasma protein binding and membrane permeability properties. Generation of [18F]-AB5186 through 18F incorporation was achieved in good radiochemical yield and subsequent in vitro and ex vivo autoradiography revealed the ability of this compound to bind with specificity to TSPO in mouse glioblastoma xenografts. Initial positron emission tomography imaging of a glioma bearing mouse and a healthy baboon support the potential for [18F]-AB5186 use as a radiotracer for non-invasive TSPO imaging in vivo

Ligand-enabled copper-mediated radioiodination of arenes

The discovery of a copper precatalyst that facilitates the key mechanistic steps of arene halodeboronation has allowed a step change in the synthesis of radioiodine-containing arenes. The active precatalyst [Cu(OAc)(phen)2]OAc was shown to perform room temperature radio-iododeboronation of aryl boronic acids with 1–2 mol % loadings and 10 min reaction times. These mild conditions enable particularly clean reactions, as demonstrated with the efficient preparation of the radiopharmaceutical and SPECT tracer, meta-iodobenzylguanidine (MIBG).Peer reviewe

Synthesis and evaluation of a radioiodinated tracer with specificity for poly(ADP-ribose) polymerase-1 (PARP-1) in vivo

Interest in nuclear imaging of poly(ADP-ribose) polymerase-1 (PARP-1) has grown in recent years due to the ability of PARP-1 to act as a biomarker for glioblastoma and increased clinical use of PARP-1 inhibitors. This study reports the identification of a lead iodinated analog 5 of the clinical PARP-1 inhibitor olaparib as a potential single-photon emission computed tomography (SPECT) imaging agent. Compound 5 was shown to be a potent PARP-1 inhibitor in cell-free and cellular assays, and it exhibited mouse plasma stability but approximately 3-fold greater intrinsic clearance when compared to olaparib. An (123)I-labeled version of 5 was generated using solid state halogen exchange methodology. Ex vivo biodistribution studies of [(123)I]-5 in mice bearing subcutaneous glioblastoma xenografts revealed that the tracer had the ability to be retained in tumour tissue and bind to PARP-1 with specificity. These findings support further investigations of [(123)I]-5 as a non-invasive PARP-1 SPECT imaging agent

Social trajectories or disrupted identities? : Changing and competing models of teacher professionalism under New Labour

Since the 1988 Education Reform Act, the teacher’s role in England has changed in many ways, a process which intensified under New Labour after 1997. Conceptions of teacher professionalism have become more structured and formalized, often heavily influenced by government policy objectives. Career paths have become more diverse and specialised. In this article, three post-1997 professional roles are given consideration as examples of these new specialised career paths: Higher Level Teaching Assistants, Teach First trainees and Advanced Skills Teachers. The article goes on to examine such developments within teaching, using Bourdieu’s concept of habitus to inform the analysis, as well as Bernstein’s theories of knowledge and identity. The article concludes that there has been considerable specialization and subsequent fragmentation of roles within the teaching profession, as part of workforce remodelling initiatives. However, there is still further scope for developing a greater sense of professional cohesion through social activism initiatives, such as the children's agenda. This may produce more stable professional identities in the future as the role of teachers within the wider children’s workforce is clarified

Network Traffic Analysis for Threats Detection in the Internet of Things

As the prevalence of the Internet of Things (IoT) continues to increase, cyber criminals are quick to exploit the security gaps that many devices are inherently designed with. Whilst users can not be expected to tackle this threat alone, many current solutions available for network monitoring are simply not accessible or can be difficult to implement for the average user and is a gap that needs to be addressed. This paper presents an effective signature-based solution to monitor, analyse and detect potentially malicious traffic for IoT ecosystems in the typical home network environment by utilising passive network sniffing techniques and a cloud-application to monitor anomalous activity. The proposed solution focuses on two attack and propagation vectors leveraged by the infamous Mirai botnet, namely DNS and Telnet. Experimental evaluation demonstrates the proposed solution can detect 98.35% of malicious DNS traffic and 99.33% of Telnet traffic respectively; for an overall detection accuracy of 98.84%

An 18F-labeled poly(ADP-ribose) polymerase positron emission tomography imaging agent

Poly(ADP-ribose) polymerase (PARP) is involved in repair of DNA breaks and is over-expressed in a wide variety of tumors, making PARP an attractive biomarker for positron emission tomography (PET) and single photon emission computed tomography imaging. Consequently, over the past decade, there has been a drive to develop nuclear imaging agents targeting PARP. Here, we report the discovery of a PET tracer that is based on the potent PARP inhibitor olaparib (1). Our lead PET tracer candidate, [18F]20, was synthesized and evaluated as a potential PARP PET radiotracer in mice bearing subcutaneous glioblastoma xenografts using ex vivo biodistribution and PET−magnetic resonance imaging techniques. Results showed that [18F]20 could be produced in a good radioactivity yield and exhibited specific PARP binding allowing visualization of tumors overexpressing PARP. [18F]20 is therefore a potential candidate radiotracer for in vivo PARP PET imaging