Improving in vitro photodynamic therapy through the development of a novel iron chelating aminolaevulinic acid prodrug

This is the final version. Available on open access from Elsevier via the DOI in this recordBackground: Photodynamic therapy (PDT) is a light activated drug therapy that can be used to treat a number of cancers and precancers. It is particularly useful in its topical form in dermatology but improvement of efficacy is required to widen its application. Methods: An ester between aminolaevulinic acid (ALA) and CP94 was synthesised (AP2-18) and experimentally evaluated to determine whether protoporphyrin IX (PpIX)-induced PDT effectiveness could be improved. A biological evaluation of AP2-18 was conducted in cultured human primary cells with both PpIX fluorescence and cell viability (as determined via the neutral red assay) being assessed in comparison to the PpIX prodrugs normally utilised in clinical practice (aminolaevulinic acid (ALA) or its methyl ester (MAL)) either administered alone or with the comparator iron chelator, CP94. Results: No significant dark toxicity was observed in human lung fibroblasts but AP2-18 significantly increased PpIX accumulation above and beyond that achieved with ALA or MAL administration +/- CP94 in both human dermal fibroblasts and epithelial squamous carcinoma cells. On light exposure, the combined hydroxypyridinone iron chelating ALA prodrug AP2-18 generated significantly greater cytotoxicity than any of the other treatment parameters investigated when the lowest concentration (250 μM) was employed. Conclusions: Newly synthesised AP2-18 is therefore concluded to be an efficacious prodrug for PpIX-induced PDT in these dermatologically relevant human cells, achieving enhanced effects at lower concentrations than currently possible with existing pharmaceuticals.Medical Research Council (MRC)Killing Cancer (UK

Regression analysis of protoporphyrin IX measurements obtained during dermatological photodynamic therapy (article)

This is the final version. Available from MDPI via the DOI in this record.The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.1103Photodynamic therapy (PDT) is a light activated drug therapy that can be used to treat a number of dermatological cancers and precancers. Improvement of efficacy is required to widen its application. Clinical protoporphyrin IX (PpIX) fluorescence data were obtained using a pre-validated, non-invasive imaging system during routine methyl aminolevulinate (MAL)-PDT treatment of 172 patients with licensed dermatological indications (37.2% actinic keratosis, 27.3% superficial basal cell carcinoma and 35.5% Bowen's disease). Linear and logistic regressions were employed to model any relationships between variables that may have affected PpIX accumulation and/or PpIX photobleaching during irradiation and thus clinical outcome at three months. Patient age was found to be associated with lower PpIX accumulation/photobleaching, however only a reduction in PpIX photobleaching appeared to consistently adversely affect treatment efficacy. Clinical clearance was reduced in lesions located on the limbs, hands and feet with lower PpIX accumulation and subsequent photobleaching adversely affecting the outcome achieved. If air cooling pain relief was employed during light irradiation, PpIX photobleaching was lower and this resulted in an approximate three-fold reduction in the likelihood of achieving clinical clearance. PpIX photobleaching during the first treatment was concluded to be an excellent predictor of clinical outcome across all lesion types.Duchy Health Charity Ltd.Killing Cancer, U

The cellular and molecular carcinogenic effects of radon exposure: a review.

Journal ArticleResearch Support, Non-U.S. Gov'tReviewOpen access articleRadon-222 is a naturally occurring radioactive gas that is responsible for approximately half of the human annual background radiation exposure globally. Chronic exposure to radon and its decay products is estimated to be the second leading cause of lung cancer behind smoking, and links to other forms of neoplasms have been postulated. Ionizing radiation emitted during the radioactive decay of radon and its progeny can induce a variety of cytogenetic effects that can be biologically damaging and result in an increased risk of carcinogenesis. Suggested effects produced as a result of alpha particle exposure from radon include mutations, chromosome aberrations, generation of reactive oxygen species, modification of the cell cycle, up or down regulation of cytokines and the increased production of proteins associated with cell-cycle regulation and carcinogenesis. A number of potential biomarkers of exposure, including translocations at codon 249 of TP53 in addition to HPRT mutations, have been suggested although, in conclusion, the evidence for such hotspots is insufficient. There is also substantial evidence of bystander effects, which may provide complications when calculating risk estimates as a result of exposure, particularly at low doses where cellular responses often appear to deviate from the linear, no-threshold hypothesis. At low doses, effects may also be dependent on cellular conditions as opposed to dose. The cellular and molecular carcinogenic effects of radon exposure have been observed to be both numerous and complex and the elevated chronic exposure of man may therefore pose a significant public health risk that may extend beyond the association with lung carcinogenesis

Overseas GP recruitment: comparing international GP training with the UK and ensuring that registration standards and patient safety are maintained

This is the final version. Available from Royal College of General Practitioners via the DOI in this record.Background Ambitious overseas recruitment targets have been set by the UK government to help alleviate the current GP shortage. European Economic Area (EEA) doctors can join the UK’s GP register under European law. Non-EEA doctors must obtain a Certificate of Eligibility for General Practice Registration (CEGPR), demonstrating equivalence to UK-trained doctors. CEGPR applications can be time-consuming and burdensome. To meet overseas recruitment targets, it is important to facilitate the most efficient route into UK general practice while maintaining registration standards and patient safety. Aim To develop a methodology to map postgraduate GP training and healthcare contextual data from an overseas country to the UK. Design & setting Desk-based research and stakeholder interviews. Method Four stages were undertaken: 1) developing a data collection template; 2) conducting a case study (using Australia as a test case); 3) refining the data collection template; and 4) creating a mapping framework. The case study used the 2016 curricula for the UK and Australia. Results Five ‘domains’ were identified: healthcare context, training pathway, curriculum, assessment, and continuing professional development (CPD) and revalidation. The final data collection template comprised 49 mapping items across the domains. The methodology incorporated the application of a red, amber, or green (RAG) rating to indicate similarity of data across the five domains. Australia was rated ‘green’ for training pathway, curriculum, and assessment, and ‘amber’ for healthcare context and CPD and revalidation. The overall rating was ‘green’. Conclusion Implementing this systematic methodology for mapping GP training between countries may support the UK’s ambitions to recruit more GPs, and alleviate current GP workforce pressures.NHS Englan

Occasional papers

no.4 (1994

tRNA-guanine transglycosylase from Escherichia coli: Recognition of dimeric, unmodified tRNATyr

In order to probe the interaction between tRNA and the tRNA hypermodifying enzyme, tRNA-guanine transglycosylase (TGT) from Escherichia coli, we have undertaken the generation of E coli tRNATyr and analogues. During efforts to adapt currently available in vitro transcription techniques we encountered difficulties attributable to dimerization of the tRNA products. E coli tRNATyr has previously been characterized for its ability to form a dimer in solutions of suitable salt concentrations at appropriate temperatures (Yang SK, Soll DG, Crothers DM (1972) Biochemistry 11, 2311-2320; Rordorff BF, Kearns DR (1976) Biochemistry 15, 3320-3330). We have applied similar techniques to our unmodified analogue of E coli tRNATyr and produced both monomeric and dimeric forms of E coli tRNATyr. In this report we find that the dimer does serve as a substrate for modification by TGT. While both the conformers are equal in terms of Vmax (within experimental error) a 2.5-fold increase in KM occurs when going from monomer to dimer. This suggests that TGT prefcrentially binds the monomer but once either conformer is bound will catalyze the modification reaction equally well. We have also compared the results for the two conformers to our previous data of an RNA minihelix corresponding to the anticodon arm of E coli tRNATyr. Here we find that our earlier conclusion, that the recognition elements for TGT are localized within the anticodon arm of cognate tRNAs, is supported.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31951/1/0000904.pd