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Antimicrobial resistance is a major challenge facing modern medicine, with an estimated 700,000 people dying annually and a global cost in excess of $100 trillion. This has led to an increased need to develop new, effective treatments. This review focuses on nitroimidazoles, which have seen a resurgence in interest due to their broad spectrum of activity against anaerobic Gram-negative and Gram-positive bacteria. The role of nitroreductases is to activate the antimicrobial by reducing the nitro group. A decrease in the activity of nitroreductases is associated with resistance. This review will discuss the resistance mechanisms of different disease organisms, including Mycobacterium tuberculosis, Helicobacter pylori and Staphylococcus aureus, and how these impact the effectiveness of specific nitroimidazoles. Perspectives in the field of nitroimidazole drug development are also summarised.
Carol Thomas; Christopher Gwenin. The Role of Nitroreductases in Resistance to Nitroimidazoles. Biology 2021, 10, 388 .
AMA StyleCarol Thomas, Christopher Gwenin. The Role of Nitroreductases in Resistance to Nitroimidazoles. Biology. 2021; 10 (5):388.
Chicago/Turabian StyleCarol Thomas; Christopher Gwenin. 2021. "The Role of Nitroreductases in Resistance to Nitroimidazoles." Biology 10, no. 5: 388.
The bacterial nitroreductase NfnB has been the focus of a great deal of research for its use in directed enzyme prodrug therapy in combination with the nitroreductase prodrug CB1954 with this combination of enzyme and prodrug even entering clinical trials. Despite some promising results, there are major limitations to this research, such as the fact that the lowest reported Km for this enzyme far exceeds the maximum dosage of CB1954. Due to these limitations, new enzymes are now being investigated for their potential use in directed enzyme prodrug therapy. One such enzyme that has proved promising is the YfkO nitroreductase from Bacillus Licheniformis. Upon investigation, the YfkO nitroreductase was shown to have a much lower Km (below the maximum dosage) than that of NfnB as well as the fact that when reacting with the prodrug it produces a much more favourable ratio of enzymatic products than NfnB, forming more of the desired 4-hydroxylamine derivative of CB1954.
Patrick Ball; Robert Hobbs; Simon Anderson; Emma Thompson; Vanessa Gwenin; Christopher Von Ruhland; Christopher Gwenin. The YfkO Nitroreductase from Bacillus Licheniformis on Gold-Coated Superparamagnetic Nanoparticles: Towards a Novel Directed Enzyme Prodrug Therapy Approach. Pharmaceutics 2021, 13, 517 .
AMA StylePatrick Ball, Robert Hobbs, Simon Anderson, Emma Thompson, Vanessa Gwenin, Christopher Von Ruhland, Christopher Gwenin. The YfkO Nitroreductase from Bacillus Licheniformis on Gold-Coated Superparamagnetic Nanoparticles: Towards a Novel Directed Enzyme Prodrug Therapy Approach. Pharmaceutics. 2021; 13 (4):517.
Chicago/Turabian StylePatrick Ball; Robert Hobbs; Simon Anderson; Emma Thompson; Vanessa Gwenin; Christopher Von Ruhland; Christopher Gwenin. 2021. "The YfkO Nitroreductase from Bacillus Licheniformis on Gold-Coated Superparamagnetic Nanoparticles: Towards a Novel Directed Enzyme Prodrug Therapy Approach." Pharmaceutics 13, no. 4: 517.
The pH drop in the hindgut of the horse is caused by lactic acid-producing bacteria which are abundant when a horse’s feeding regime is excessively carbohydrate rich. This drop in pH below six causes hindgut acidosis and may lead to laminitis. Lactic acid-producing bacteria Streptococcus equinus and Mitsuokella jalaludinii have been found to produce high amounts of L-lactate and D-lactate, respectively. Early detection of increased levels of these bacteria could allow the horse owner to tailor the horse’s diet to avoid hindgut acidosis and subsequent laminitis. Therefore, 16s ribosomal ribonucleic acid (rRNA) sequences were identified and modified to obtain target single stranded deoxyribonucleic acid (DNA) from these bacteria. Complementary single stranded DNAs were designed from the modified target sequences to form capture probes. Binding between capture probe and target single stranded deoxyribonucleic acid (ssDNA) in solution has been studied by gel electrophoresis. Among pairs of different capture probes and target single stranded DNA, hybridization of Streptococcus equinus capture probe 1 (SECP1) and Streptococcus equinus target 1 (SET1) was portrayed as gel electrophoresis. Adsorptive stripping voltammetry was utilized to study the binding of thiol modified SECP1 over gold on glass substrates and these studies showed a consistent binding signal of thiol modified SECP1 and their hybridization with SET1 over the gold working electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to examine the binding of thiol modified SECP1 on the gold working electrode and hybridization of thiol modified SECP1 with the target single stranded DNA. Both demonstrated the gold working electrode surface was modified with a capture probe layer and hybridization of the thiol bound ssDNA probe with target DNA was indicated. Therefore, the proposed electrochemical biosensor has the potential to be used for the detection of the non-synthetic bacterial DNA target responsible for equine hindgut acidosis.
Joshua Davies; Carol Thomas; Mohammad Rizwan; Christopher Gwenin. Development of Electrochemical DNA Biosensor for Equine Hindgut Acidosis Detection. Sensors 2021, 21, 2319 .
AMA StyleJoshua Davies, Carol Thomas, Mohammad Rizwan, Christopher Gwenin. Development of Electrochemical DNA Biosensor for Equine Hindgut Acidosis Detection. Sensors. 2021; 21 (7):2319.
Chicago/Turabian StyleJoshua Davies; Carol Thomas; Mohammad Rizwan; Christopher Gwenin. 2021. "Development of Electrochemical DNA Biosensor for Equine Hindgut Acidosis Detection." Sensors 21, no. 7: 2319.
This review examines the stress hormone cortisol which plays an important role in regulating and supporting different bodily functions. Disruption in cortisol production has an impact on health and this review looks at a wide range of papers where cortisol has been indicated as a factor in numerous chronic conditions—especially those which are classed as “noncommunicable diseases” (NCDs). Timely detection, screening, and treatment for NCDs are vital to address the growing problem of NCDs worldwide—this would have health and socioeconomic benefits. Interestingly, many of the papers highlight the pro‐inflammatory consequences of cortisol dysregulation and its deleterious effects on the body. This is particularly relevant given the recent findings concerning COVID‐19 where pro‐inflammatory cytokines have been implicated in severe inflammation.
Carol Jones; Christopher Gwenin. Cortisol level dysregulation and its prevalence—Is it nature's alarm clock? Physiological Reports 2020, 8, e14644 .
AMA StyleCarol Jones, Christopher Gwenin. Cortisol level dysregulation and its prevalence—Is it nature's alarm clock? Physiological Reports. 2020; 8 (24):e14644.
Chicago/Turabian StyleCarol Jones; Christopher Gwenin. 2020. "Cortisol level dysregulation and its prevalence—Is it nature's alarm clock?" Physiological Reports 8, no. 24: e14644.
Directed enzyme prodrug therapy (DEPT) is a cancer chemotherapy strategy in which bacterial enzymes are delivered to a cancer site before prodrug administration, resulting in prodrug activation at the cancer site and more localized treatment. A major limitation to DEPT is the poor effectiveness of the most studied enzyme for the CB1954 prodrug, NfnB from Escherichia coli, at concentrations suitable for human use. Much research into finding alternative enzymes to NfnB has resulted in the identification of the Xenobiotic reductases, XenA and XenB, which have been shown in the literature to reduce environmentally polluting nitro‐compounds. In this study, they were assessed for their potential use in cancer prodrug therapy strategies. Both proteins were cloned into the pET28a+ expression vector to give the genetically modified proteins XenA‐his and XenB‐his, of which only XenB‐his was active when tested with CB1954. XenB‐his was further modified to include a cysteine‐tag to facilitate direct immobilization on to a gold surface for future magnetic nanoparticle DEPT (MNDEPT) treatments and was named XenB‐cys. When tested using high‐performance liquid chromatography (HPLC), XenB‐his and XenB‐cys both demonstrated a preference for reducing CB1954 at the 4‐nitro position. Furthermore, XenB‐his and XenB‐cys successfully induced cell death in SK‐OV‐3 cells when combined with CB1954. This led to XenB‐cys being identified as a promising candidate for use in future MNDEPT treatments.
Patrick Ball; Jennifer Halliwell; Simon Anderson; Vanessa Gwenin; Christopher Gwenin. Evaluation of two xenobiotic reductases fromPseudomonas putidafor their suitability for magnetic nanoparticle‐directed enzyme prodrug therapy as a novel approach to cancer treatment. MicrobiologyOpen 2020, 9, 1 .
AMA StylePatrick Ball, Jennifer Halliwell, Simon Anderson, Vanessa Gwenin, Christopher Gwenin. Evaluation of two xenobiotic reductases fromPseudomonas putidafor their suitability for magnetic nanoparticle‐directed enzyme prodrug therapy as a novel approach to cancer treatment. MicrobiologyOpen. 2020; 9 (10):1.
Chicago/Turabian StylePatrick Ball; Jennifer Halliwell; Simon Anderson; Vanessa Gwenin; Christopher Gwenin. 2020. "Evaluation of two xenobiotic reductases fromPseudomonas putidafor their suitability for magnetic nanoparticle‐directed enzyme prodrug therapy as a novel approach to cancer treatment." MicrobiologyOpen 9, no. 10: 1.
Population extended life expectancy has significantly increased the risk of septic shock in an ageing population. Sepsis affects roughly 20 million people every year, resulting in over 11 million deaths. The need for faster more accurate diagnostics and better management is therefore paramount in the fight to prevent these avoidable deaths. Here we report the development of a POC device with the ability to identify a broad range of pathogens on a lateral flow platform. Namely Gram-positive and Gram-negative bacteria. The simple to use laboratory device has the potential to be automated, thus enabling an operator to carry out solid-phase lysis and room temperature RPA in situ, providing accurate results in hours rather than days. Results show there is a potential for a fully automated device in which concepts described in this paper can be integrated into a lateral flow device.
Alice Jane Heeroma; Christopher Gwenin. Development of Solid-Phase RPA on a Lateral Flow Device for the Detection of Pathogens Related to Sepsis. Sensors 2020, 20, 4182 .
AMA StyleAlice Jane Heeroma, Christopher Gwenin. Development of Solid-Phase RPA on a Lateral Flow Device for the Detection of Pathogens Related to Sepsis. Sensors. 2020; 20 (15):4182.
Chicago/Turabian StyleAlice Jane Heeroma; Christopher Gwenin. 2020. "Development of Solid-Phase RPA on a Lateral Flow Device for the Detection of Pathogens Related to Sepsis." Sensors 20, no. 15: 4182.
Directed enzyme prodrug therapy (DEPT) involves the delivery of a prodrug-activating enzyme to a solid tumour site, followed by the subsequent activation of an administered prodrug. One of the most studied enzyme–prodrug combinations is the nitroreductase from Escherichia coli (NfnB) with the prodrug CB1954 [5-(aziridin-1-yl)-2,4-dinitro-benzamide]. One of the major issues faced by DEPT is the ability to successfully internalize the enzyme into the target cells. NfnB has previously been genetically modified to contain cysteine residues (NfnB-Cys) which bind to gold nanoparticles for a novel DEPT therapy called magnetic nanoparticle directed enzyme prodrug therapy (MNDEPT). One cellular internalisation method is the use of cell-penetrating peptides (CPPs), which aid cellular internalization of cargo. Here the cell-penetrating peptides: HR9 and Pep-1 were tested for their ability to conjugate with NfnB-Cys. The conjugates were further tested for their potential use in MNDEPT, as well as conjugating with the delivery vector intended for use in MNDEPT and tested for the vectors capability to penetrate into cells.
Simon D. Anderson; Robert J. Hobbs; Gwenin; Patrick Ball; Lindsey A. Bennie; Jonathan A. Coulter; Ball; Vanessa V. Gwenin; Chris D. Gwenin; Vanessa V Gwenin; Chris Gwenin; Vanessa V. Gwenin; Chris D. Gwenin. Cell-Penetrating Peptides as a Tool for the Cellular Uptake of a Genetically Modified Nitroreductase for use in Directed Enzyme Prodrug Therapy. Journal of Functional Biomaterials 2019, 10, 45 .
AMA StyleSimon D. Anderson, Robert J. Hobbs, Gwenin, Patrick Ball, Lindsey A. Bennie, Jonathan A. Coulter, Ball, Vanessa V. Gwenin, Chris D. Gwenin, Vanessa V Gwenin, Chris Gwenin, Vanessa V. Gwenin, Chris D. Gwenin. Cell-Penetrating Peptides as a Tool for the Cellular Uptake of a Genetically Modified Nitroreductase for use in Directed Enzyme Prodrug Therapy. Journal of Functional Biomaterials. 2019; 10 (4):45.
Chicago/Turabian StyleSimon D. Anderson; Robert J. Hobbs; Gwenin; Patrick Ball; Lindsey A. Bennie; Jonathan A. Coulter; Ball; Vanessa V. Gwenin; Chris D. Gwenin; Vanessa V Gwenin; Chris Gwenin; Vanessa V. Gwenin; Chris D. Gwenin. 2019. "Cell-Penetrating Peptides as a Tool for the Cellular Uptake of a Genetically Modified Nitroreductase for use in Directed Enzyme Prodrug Therapy." Journal of Functional Biomaterials 10, no. 4: 45.
A toxin is a poisonous substance produced within living cells or organisms. One of the most potent groups of toxins currently known are the Botulinum Neurotoxins (BoNTs). These are so deadly that as little as 62 ng could kill an average human; to put this into context that is approximately 200,000 × less than the weight of a grain of sand. The extreme toxicity of BoNTs leads to the need for methods of determining their concentration at very low levels of sensitivity. Currently the mouse bioassay is the most widely used detection method monitoring the activity of the toxin; however, this assay is not only lengthy, it also has both cost and ethical issues due to the use of live animals. This review focuses on detection methods both existing and emerging that remove the need for the use of animals and will look at three areas; speed of detection, sensitivity of detection and finally cost. The assays will have wide reaching interest, ranging from the pharmaceutical/clinical industry for production quality management or as a point of care sensor in suspected cases of botulism, the food industry as a quality control measure, to the military, detecting BoNT that has been potentially used as a bio warfare agent.
Robert J. Hobbs; Carol A. Thomas; Jennifer Halliwell; Christopher D. Gwenin. Rapid Detection of Botulinum Neurotoxins—A Review. Toxins 2019, 11, 418 .
AMA StyleRobert J. Hobbs, Carol A. Thomas, Jennifer Halliwell, Christopher D. Gwenin. Rapid Detection of Botulinum Neurotoxins—A Review. Toxins. 2019; 11 (7):418.
Chicago/Turabian StyleRobert J. Hobbs; Carol A. Thomas; Jennifer Halliwell; Christopher D. Gwenin. 2019. "Rapid Detection of Botulinum Neurotoxins—A Review." Toxins 11, no. 7: 418.
Medicine is constantly looking for new and improved treatments for diseases, which need to have a high efficacy and be cost-effective, creating a large demand on scientific research to discover such new treatments. One important aspect of any treatment is the ability to be able to target only the illness and not cause harm to another healthy part of the body. For this reason, metallic nanoparticles have been and are currently being extensively researched for their possible medical uses, including medical imaging, antibacterial and antiviral applications. Superparamagnetic metal nanoparticles possess properties that allow them to be directed around the body with a magnetic field or directed to a magnetic implant, which opens up the potential to conjugate various bio-cargos to the nanoparticles that could then be directed for treatment in the body. Here we report on some of the current bio-medical applications of various metal nanoparticles, including single metal nanoparticles, functionalized metal nanoparticles, and core-shell metal nanoparticles using a core of Fe3O4 as well as synthesis methods of these core-shell nanoparticles.
Simon Anderson; Vanessa V. Gwenin; Christopher D. Gwenin. Magnetic Functionalized Nanoparticles for Biomedical, Drug Delivery and Imaging Applications. Nanoscale Research Letters 2019, 14, 1 -16.
AMA StyleSimon Anderson, Vanessa V. Gwenin, Christopher D. Gwenin. Magnetic Functionalized Nanoparticles for Biomedical, Drug Delivery and Imaging Applications. Nanoscale Research Letters. 2019; 14 (1):1-16.
Chicago/Turabian StyleSimon Anderson; Vanessa V. Gwenin; Christopher D. Gwenin. 2019. "Magnetic Functionalized Nanoparticles for Biomedical, Drug Delivery and Imaging Applications." Nanoscale Research Letters 14, no. 1: 1-16.
Directed enzyme prodrug therapy is a chemotherapy strategy that utilises prodrug-activating enzymes to activate prodrugs at the tumour location, thus reducing off-target effects. The most commonly investigated enzyme for use with the CB1954 prodrug is the NfnB nitroreductase from E. coli. Literature states that CB1954 is reduced by NfnB at the 2- or 4-position at a 1:1 ratio; deviation from this ratio has been observed in the literature, but not further investigated. The kinetic parameters for the genetically-modified enzymes; NfnB-his, NfnB-cys and AuNP-NfnB-cys were assessed and HPLC analysis was used to determine the hydroxylamine product ratios formed when reacted with CB1954. Time-dependent HPLC studies were carried out to assess how this ratio changes over time. It was shown that the hydroxylamine ratio formed by the reduction of CB1954 by a nitroreductase changes over time and that this change in ratio relates directly to the kinetics of the reaction. Thus, the hydroxylamine ratio measured using HPLC at a given time point was not a true indication of the preference of the nitroreductase enzymes during catalysis. These results question how nitroreductases are evaluated in terms of the hydroxylamine ratio and it is suspected that this phenomenon may also apply to other enzyme/prodrug combinations.
Patrick Ball; Emma Thompson; Simon Anderson; Vanessa Gwenin; Chris Gwenin. Time dependent HPLC analysis of the product ratio of enzymatically reduced prodrug CB1954 by a modified and immobilised nitroreductase. European Journal of Pharmaceutical Sciences 2018, 127, 217 -224.
AMA StylePatrick Ball, Emma Thompson, Simon Anderson, Vanessa Gwenin, Chris Gwenin. Time dependent HPLC analysis of the product ratio of enzymatically reduced prodrug CB1954 by a modified and immobilised nitroreductase. European Journal of Pharmaceutical Sciences. 2018; 127 ():217-224.
Chicago/Turabian StylePatrick Ball; Emma Thompson; Simon Anderson; Vanessa Gwenin; Chris Gwenin. 2018. "Time dependent HPLC analysis of the product ratio of enzymatically reduced prodrug CB1954 by a modified and immobilised nitroreductase." European Journal of Pharmaceutical Sciences 127, no. : 217-224.
Victor O. Ebuele; Daniel G. Congrave; Chris Gwenin; Vera Fitzsimmons-Thoss. Development of a Cobalt Electrode for the Determination of Phosphate in Soil Extracts and Comparison with Standard Methods. Analytical Letters 2017, 51, 834 -848.
AMA StyleVictor O. Ebuele, Daniel G. Congrave, Chris Gwenin, Vera Fitzsimmons-Thoss. Development of a Cobalt Electrode for the Determination of Phosphate in Soil Extracts and Comparison with Standard Methods. Analytical Letters. 2017; 51 (6):834-848.
Chicago/Turabian StyleVictor O. Ebuele; Daniel G. Congrave; Chris Gwenin; Vera Fitzsimmons-Thoss. 2017. "Development of a Cobalt Electrode for the Determination of Phosphate in Soil Extracts and Comparison with Standard Methods." Analytical Letters 51, no. 6: 834-848.
During pulmonary tuberculosis (PTB) antibodies are generated to trehalose esters of mycolic acids which are cell wall lipids of Mycobacterium tuberculosis (Mtb). Attempts have been made to use these complex natural mixtures in serological tests for PTB diagnosis. The aim of this work was to determine whether a serological test based on a panel of defined individual trehalose esters of characteristic synthetic mycolic acids has improved diagnostic accuracy in distinguishing patients with culture positive PTB from individuals who were Mtb culture negative. One hundred serum samples from well-characterized patients with presumptive tuberculosis, and diagnosed as having pulmonary smear and culture positive TB, or being culture and smear negative were evaluated by ELISA using different combinations of synthetic antigens and secondary antibodies. Using cut-off values determined from these samples, we validated this study blind in samples from a further 249 presumptive TB patients. With the first 100 samples, detailed responses depended both on the precise structure of the antigen and on the secondary antibody. Using a single antigen, a sensitivity/specificity combination for smear and culture positive PTB detection of 85 and 88% respectively was achieved; this increased to 96% and 95% respectively by a statistical combination of the results with seven antigens. In the blind study a sensitivity/specificity of 87% and 83% was reached with a single antigen. With some synthetic antigens, the responses from all 349 samples were significantly better than those with the natural mixture. Combining the results for seven antigens allowed a distinction between culture positive and negative with a ROC AUC of 0.95. We have identified promising antigen candidates for serological assays that could be used to diagnose PTB and which could be the basis of a much-needed, simple, rapid diagnostic test that would bring care closer to communities.
Alison Jones; Mark Pitts; Juma’A R. Al Dulayymi; James Gibbons; Andrew Ramsay; Delia Goletti; Chris Gwenin; Mark S. Baird. New synthetic lipid antigens for rapid serological diagnosis of tuberculosis. PLOS ONE 2017, 12, e0181414 .
AMA StyleAlison Jones, Mark Pitts, Juma’A R. Al Dulayymi, James Gibbons, Andrew Ramsay, Delia Goletti, Chris Gwenin, Mark S. Baird. New synthetic lipid antigens for rapid serological diagnosis of tuberculosis. PLOS ONE. 2017; 12 (8):e0181414.
Chicago/Turabian StyleAlison Jones; Mark Pitts; Juma’A R. Al Dulayymi; James Gibbons; Andrew Ramsay; Delia Goletti; Chris Gwenin; Mark S. Baird. 2017. "New synthetic lipid antigens for rapid serological diagnosis of tuberculosis." PLOS ONE 12, no. 8: e0181414.
Hanan M. Ali; Gani Koza; Rwoa'A Hameed; Richard Rowles; Carys Davies; Juma'a R. Al Dulayymi; Chris Gwenin; Mark Baird. The synthesis of single enantiomers of trans-alkene containing mycolic acids and related sugar esters. Tetrahedron 2016, 72, 7143 -7158.
AMA StyleHanan M. Ali, Gani Koza, Rwoa'A Hameed, Richard Rowles, Carys Davies, Juma'a R. Al Dulayymi, Chris Gwenin, Mark Baird. The synthesis of single enantiomers of trans-alkene containing mycolic acids and related sugar esters. Tetrahedron. 2016; 72 (45):7143-7158.
Chicago/Turabian StyleHanan M. Ali; Gani Koza; Rwoa'A Hameed; Richard Rowles; Carys Davies; Juma'a R. Al Dulayymi; Chris Gwenin; Mark Baird. 2016. "The synthesis of single enantiomers of trans-alkene containing mycolic acids and related sugar esters." Tetrahedron 72, no. 45: 7143-7158.
The synthesis of single mono-arabino mycolates, important lipid antigens from mycobacteria is described, using structurally defined synthetic mycolic acids. Preliminary assays indicate that these are differentially antigenic to antibodies in the serum of people with active tuberculosis. Graphical
Mohsin O. Mohammed; Mark S. Baird; Alison Jones; Chris Gwenin; Juma'a R. Al Dulayymi. Arabino mycolates from synthetic mycolic acids. Tetrahedron 2016, 72, 2849 -2857.
AMA StyleMohsin O. Mohammed, Mark S. Baird, Alison Jones, Chris Gwenin, Juma'a R. Al Dulayymi. Arabino mycolates from synthetic mycolic acids. Tetrahedron. 2016; 72 (22):2849-2857.
Chicago/Turabian StyleMohsin O. Mohammed; Mark S. Baird; Alison Jones; Chris Gwenin; Juma'a R. Al Dulayymi. 2016. "Arabino mycolates from synthetic mycolic acids." Tetrahedron 72, no. 22: 2849-2857.
Directed enzyme prodrug therapy is a form of cancer chemotherapy in which bacterial prodrug-activating enzymes, or their encoding genes, are directed to the tumour before administration of a prodrug. The prodrug can then be activated into a toxic drug at the tumour site, reducing off-target effects. The bacterial nitroreductases are a class of enzymes used in this therapeutic approach and although very promising, the low turnover rate of prodrug by the most studied nitroreductase enzyme, NfnB from Escherichia coli (NfnB_Ec), is a major limit to this technology. There is a continual search for enzymes with greater efficiency, and as part of the search for more efficient bacterial nitroreductase enzymes, two novel enzymes from Bacillus cereus (strain ATCC 14579) have been identified and shown to reduce the CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide) prodrug to its respective 2′-and 4′-hydroxylamine products. Both enzymes shared features characteristic of the nitro-FMN-reductase superfamily including non-covalently associated FMN, requirement for the NAD(P)H cofactor, homodimeric, could be inhibited by Dicoumarol (3,3′-methylenebis(4-hydroxy-2H-chromen-2-one)), and displayed ping pong bi bi kinetics. Based on the biochemical characteristics and nucleotide alignment with other nitroreductase enzymes, one enzyme was named YdgI_Bc and the other YfkO_Bc. Both B. cereus enzymes had greater turnover for the CB1954 prodrug compared with NfnB_Ec, and in the presence of added NADPH cofactor, YfkO_Bc had superior cell killing ability, and produced mainly the 4′-hydroxylamine product at low prodrug concentration. The YfkO_Bc was identified as a promising candidate for future enzyme prodrug therapy.
Vanessa V. Gwenin; Paramasivan Poornima; Jennifer Halliwell; Patrick Ball; George Robinson; Chris D. Gwenin. Identification of novel nitroreductases from Bacillus cereus and their interaction with the CB1954 prodrug. Biochemical Pharmacology 2015, 98, 392 -402.
AMA StyleVanessa V. Gwenin, Paramasivan Poornima, Jennifer Halliwell, Patrick Ball, George Robinson, Chris D. Gwenin. Identification of novel nitroreductases from Bacillus cereus and their interaction with the CB1954 prodrug. Biochemical Pharmacology. 2015; 98 (3):392-402.
Chicago/Turabian StyleVanessa V. Gwenin; Paramasivan Poornima; Jennifer Halliwell; Patrick Ball; George Robinson; Chris D. Gwenin. 2015. "Identification of novel nitroreductases from Bacillus cereus and their interaction with the CB1954 prodrug." Biochemical Pharmacology 98, no. 3: 392-402.
Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A–E) using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins.
Alison C. Savage; Nicholas Buckley; Jennifer Halliwell; Christopher Gwenin. Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy. Toxins 2015, 7, 1544 -1555.
AMA StyleAlison C. Savage, Nicholas Buckley, Jennifer Halliwell, Christopher Gwenin. Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy. Toxins. 2015; 7 (5):1544-1555.
Chicago/Turabian StyleAlison C. Savage; Nicholas Buckley; Jennifer Halliwell; Christopher Gwenin. 2015. "Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy." Toxins 7, no. 5: 1544-1555.
This paper studies the effects of different numbers of linkers on half-squaraine dyes in DSC devices.
Arthur Connell; Peter J. Holliman; Eurig W. Jones; Leo Furnell; Christopher Kershaw; Matthew Davies; Chris Gwenin; Mateusz B. Pitak; Simon J. Coles; Graeme Cooke. Multiple linker half-squarylium dyes for dye-sensitized solar cells; are two linkers better than one? Journal of Materials Chemistry A 2014, 3, 2883 -2894.
AMA StyleArthur Connell, Peter J. Holliman, Eurig W. Jones, Leo Furnell, Christopher Kershaw, Matthew Davies, Chris Gwenin, Mateusz B. Pitak, Simon J. Coles, Graeme Cooke. Multiple linker half-squarylium dyes for dye-sensitized solar cells; are two linkers better than one? Journal of Materials Chemistry A. 2014; 3 (6):2883-2894.
Chicago/Turabian StyleArthur Connell; Peter J. Holliman; Eurig W. Jones; Leo Furnell; Christopher Kershaw; Matthew Davies; Chris Gwenin; Mateusz B. Pitak; Simon J. Coles; Graeme Cooke. 2014. "Multiple linker half-squarylium dyes for dye-sensitized solar cells; are two linkers better than one?" Journal of Materials Chemistry A 3, no. 6: 2883-2894.
The standard method for the detection of botulinum neurotoxin is currently the mouse bioassay which is considered to be the most reliable method for the detection of the active form of this toxin. Despite this it is a time-consuming and expensive assay to run and as such many alternative assays have recently been proposed. Herein we report the development of two electrochemical assays for the detection of active botulinum neurotoxin in a pharmaceutical sample. Gold electrodes were modified with self-assembled monolayers of the SNARE protein SNAP-25 which is selectively cleaved by active botulinum neurotoxin A. Cyclic voltammetry and electrochemical impedance spectroscopy were performed on the modified working electrodes to observe changes to the layer on addition of the toxin. Both methods were able to distinguish the difference between the presence of the active toxin and a placebo containing the excipients of the pharmaceutical product. The electrochemical impedance spectroscopy assay also allowed for detection of the active toxin at concentrations as low as 25fg/ml, with results being obtained in under an hour outperforming the mouse bioassay
Jennifer Halliwell; Alison Savage; Nicholas Buckley; Christopher Gwenin. Electrochemical impedance spectroscopy biosensor for detection of active botulinum neurotoxin. Sensing and Bio-Sensing Research 2014, 2, 12 -15.
AMA StyleJennifer Halliwell, Alison Savage, Nicholas Buckley, Christopher Gwenin. Electrochemical impedance spectroscopy biosensor for detection of active botulinum neurotoxin. Sensing and Bio-Sensing Research. 2014; 2 ():12-15.
Chicago/Turabian StyleJennifer Halliwell; Alison Savage; Nicholas Buckley; Christopher Gwenin. 2014. "Electrochemical impedance spectroscopy biosensor for detection of active botulinum neurotoxin." Sensing and Bio-Sensing Research 2, no. : 12-15.
This paper reports the synthesis of a series of new half-squaraine dyes (Hf-SQ) based around a common chromophoric unit but with differently positioned linker groups.
Arthur Connell; Peter J. Holliman; Matthew Davies; Chris Gwenin; Sophie Weiss; Mateusz Pitak; Peter N. Horton; Simon Coles; Graeme Cooke. A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells. Journal of Materials Chemistry A 2014, 2, 4055 -4066.
AMA StyleArthur Connell, Peter J. Holliman, Matthew Davies, Chris Gwenin, Sophie Weiss, Mateusz Pitak, Peter N. Horton, Simon Coles, Graeme Cooke. A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells. Journal of Materials Chemistry A. 2014; 2 (11):4055-4066.
Chicago/Turabian StyleArthur Connell; Peter J. Holliman; Matthew Davies; Chris Gwenin; Sophie Weiss; Mateusz Pitak; Peter N. Horton; Simon Coles; Graeme Cooke. 2014. "A study of dye anchoring points in half-squarylium dyes for dye-sensitized solar cells." Journal of Materials Chemistry A 2, no. 11: 4055-4066.
Botulinum neurotoxins are one of the most potent toxins known to man. Current methods of detection involve the quantification of the toxin but do not take into account the percentage of the toxin that is active. At present the assay used for monitoring the activity of the toxin is the mouse bioassay, which is lengthy and has ethical issues due to the use of live animals. This report demonstrates a novel assay that utilises the endopeptidase activity of the toxin to detect Botulinum neurotoxin in a pharmaceutical sample. The cleaving of SNAP-25 is monitored via UV-Visible spectroscopy with a limit of detection of 373 fg/mL and has been further developed into a high throughput method using a microplate reader detecting down to 600 fg/mL of active toxin. The results show clear differences between the toxin product and the placebo, which contains the pharmaceutical excipients human serum albumin and lactose, showing that the assay detects the active form of the toxin.
Jennifer Halliwell; Christopher Gwenin. A Label Free Colorimetric Assay for the Detection of Active Botulinum Neurotoxin Type A by SNAP-25 Conjugated Colloidal Gold. Toxins 2013, 5, 1381 -1391.
AMA StyleJennifer Halliwell, Christopher Gwenin. A Label Free Colorimetric Assay for the Detection of Active Botulinum Neurotoxin Type A by SNAP-25 Conjugated Colloidal Gold. Toxins. 2013; 5 (8):1381-1391.
Chicago/Turabian StyleJennifer Halliwell; Christopher Gwenin. 2013. "A Label Free Colorimetric Assay for the Detection of Active Botulinum Neurotoxin Type A by SNAP-25 Conjugated Colloidal Gold." Toxins 5, no. 8: 1381-1391.