The effects of protoporphyrin IX-induced photodynamic therapy with and without iron chelation on human squamous carcinoma cells cultured under normoxic, hypoxic and hyperoxic conditions.

BACKGROUND: Photodynamic therapy requires the combined interaction of a photosensitiser, light and oxygen to ablate target tissue. In this study we examined the effect of iron chelation and oxygen environment manipulation on the accumulation of the clinically useful photosensitiser protoporphyrin IX (PpIX) within human squamous epithelial carcinoma cells and the subsequent ablation of these cells on irradiation. METHODS: Cells were incubated at concentrations of 5%, 20% or 40% oxygen for 24h prior to and for 3h following the administration of the PpIX precursors aminolevulinic acid (ALA), methyl aminolevulinate (MAL) or hexylaminolevulinate (HAL) with or without the iron chelator 1,2-diethyl-3-hydroxypyridin-4-one hydrochloride (CP94). PpIX accumulation was monitored using a fluorescence plate reader, cells were irradiated with 37 J/cm(2) red light and cell viability measured using the neutral red uptake assay. RESULTS: Manipulation of the oxygen environment and/or co-administration of CP94 with PpIX precursors resulted in significant changes in both PpIX accumulation and photobleaching. Incubation with 5% or 40% oxygen produced the greatest levels of PpIX and photobleaching in cells incubated with ALA/MAL. Incorporation of CP94 also resulted in significant decreases in cell viability following administration of ALA/MAL/HAL, with oxygen concentration predominantly having a significant effect in cells incubated with HAL. CONCLUSIONS: Experimentation with human squamous epithelial carcinoma cells has indicated that the iron chelator CP94 significantly increased PpIX accumulation induced by each PpIX congener investigated (ALA/MAL/HAL) at all oxygen concentrations employed (5%/20%/40%) resulting in increased levels of photobleaching and reduced cell viability on irradiation. Further detailed investigation of the complex relationship of PDT cytotoxicity at various oxygen concentrations is required. It is therefore concluded that iron chelation with CP94 is a simple protocol modification with which it may be much easier to enhance clinical PDT efficacy than the complex and less well understood process of oxygen manipulation

An in vitro comparison of the effects of the iron-chelating agents, CP94 and dexrazoxane, on protoporphyrin IX accumulation for photodynamic therapy and/or fluorescence guided resection.

Comparative StudyJournal Article"This is the peer reviewed version of the following article:Photochemistry and Photobiology, Volume 87, Issue 6, pages 1419–1426, November/December 2011, which has been published in final form at http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1751-1097.2011.00985.x/full. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."Photodynamic therapy (PDT) utilizes the combined interaction of a photosensitizer, light and molecular oxygen to ablate tumor tissue. Maximizing the accumulation of the photosensitizer protoporphyrin IX (PpIX) within different cell types would be clinically useful. Dermatological PpIX-induced PDT regimes produce good clinical outcomes but this currently only applies when the lesion remains superficial. Also, as an adjuvant therapy for the treatment of primary brain tumors, fluorescence guided resection (FGR) and PDT can be used to highlight and destroy tumor cells unreachable by surgical resection. By employing iron chelators PpIX accumulation can be enhanced. Two iron-chelating agents, 1,2-diethyl-3-hydroxypyridin-4-one hydrochloride (CP94) and dexrazoxane, were individually combined with the porphyrin precursors aminolevulinic acid (ALA), methyl aminolevulinate (MAL) and hexyl aminolevulinate (HAL). Efficacies of the iron-chelating agents were compared by recording the PpIX fluorescence in human squamous epithelial carcinoma cells (A431) and human glioma cells (U-87 MG) every hour for up to 6 h. Coincubation of ALA/MAL/HAL with CP94 resulted in a greater accumulation of PpIX compared to that produced by coincubation of these congeners with dexrazoxane. Therefore the clinical employment of iron chelation, particularly with CP94 could potentially increase and/or accelerate the accumulation of ALA/MAL/HAL-induced PpIX for PDT or FGR

Status epilepticus on the paediatric intensive care unit—the role of EEG monitoring

AbstractA pilot study was undertaken of the feasibility of continuous EEG monitoring of patients admitted to a Paediatric Intensive Care Unit (PICU) for management of status epilepticus or its immediate sequelae. Eight children were studied and seizure activity was recorded in four patients. Additional information influencing management was obtained: the bedside nurse considered decerebrate posturing in one patient to be a seizure: there were no epileptiform EEG changes. Another patient was considered to have seizures (clonic movements of both upper limbs) following cardiac arrest; the EEG showed electrocerebral silence, and thiopentone treatment was discontinued. In another patient, continuing epileptiform activity on EEG gave intensivists the confidence to use higher than usual doses of thiopentone. The problems encountered were delays in monitoring, once for a CT scan and once because of two admissions within hours of each other. We conclude that EEG monitoring on a PICU is feasible and provides clinically useful information

Supporting location-based inquiry learning across school, field and home contexts

Here we explore how technology can be applied to support inquiry learning spanning a range of contexts. The development process of a location-based inquiry learning toolset is presented for a secondary school GCSE Geography project. The design framework used and the process of participatory development is discussed with regard to the co-development of the activities and tools involved in an inquiry project. The lessons learned relate to the formation of a motivational context for the inquiry; the role of personal data collection in the field; the use of bridging representations across field and classroom activities; and the development of flexible, re-usable tools to support and bridge sequences of activities

Challenges in personalisation: supporting mobile science inquiry learning across contexts

The Personal Inquiry project (PI) aimed to develop and implement personal inquiries in secondary schools in order to motivate engagement in scientific inquiry through its focus on inquiries of personal interest to young learners. This paper describes the authors’ experiences working with teachers in one school over three years, iteratively developing the nQuire toolkit* and pedagogical support across different inquiries which can be used in and across different contexts, ranging from the classroom to field trips and at home. As nQuire is web based, and can be accessed in different locations and on a range of networked devices it supports mobile inquiry learning and is the main resource for bridging between contexts. This paper discusses issues related to developing personal inquiries in schools, working across different contexts and focusing on three aspects of personalisation: choice, personal relevance and learner responsibility. It discusses the challenges faced when developing personalised inquiries in science, both in more traditional classroom contexts and in the less formal environment of an after school club. Drawing on technology supported inquiries from both these contexts it reflects on some of the constraints and tensions in providing learners with choice in their inquiries, identifying both the constraints and successes

Effect of an oxygen pressure injection (OPI) device on the oxygen saturation of patients during dermatological methyl aminolevulinate photodynamic therapy

Journal Article“The final publication is available at Springer via http://dx.doi.org/10.1007/s10103-012-1188-y"Methyl aminolevulinate photodynamic therapy (MAL-PDT) (a topical treatment used for a number of precancerous skin conditions) utilizes the combined interaction of a photosensitizer (protoporphyrin IX (PpIX)), light of the appropriate wavelength, and molecular oxygen to produce singlet oxygen and other reactive oxygen species which induce cell death. During treatment, localized oxygen depletion occurs and is thought to contribute to decreased efficacy. The aim of this study was to investigate whether an oxygen pressure injection (OPI) device had an effect on localized oxygen saturation levels and/or PpIX fluorescence of skin lesions during MAL-PDT. This study employed an OPI device to apply oxygen under pressure to the skin lesions of patients undergoing standard MAL-PDT. Optical reflectance spectrometry and fluorescence imaging were used to noninvasively monitor the localized oxygen saturation and PpIX fluorescence of the treatment area, respectively. No significant changes in oxygen saturation were observed when these data were combined for the group with OPI and compared to the group that received standard MAL-PDT without OPI. Additionally, no significant difference in PpIX photobleaching or clinical outcome at 3 months between the groups of patients was observed, although the group that received standard MAL-PDT demonstrated a significant increase (p < 0.05) in PpIX fluorescence initially and both groups produced a significant decrease (p < 0.05) after light irradiation. In conclusion, with this sample size, this OPI device was not found to be an effective method with which to improve tissue oxygenation during MAL-PDT. Further investigation is therefore required to find a more effective method of MAL-PDT enhancement. © 2012 Springer-Verlag London Ltd

The time-dependent accumulation of protoporphyrin IX fluorescence in nodular basal cell carcinoma following application of methyl aminolevulinate with an oxygen pressure injection device

Clinical TrialJournal ArticleAuthor's post-print is subject to a Creative Commons Attribution Non-Commercial No Derivatives LicenseTopical protoporphyrin (PpIX)-induced photodynamic therapy (PDT) relies on the penetration of the prodrug into the skin lesion and subsequent accumulation of the photosensitizer. Methyl aminolevulinate (MAL)-PDT is an established treatment for thinner and superficial non-melanoma skin cancers (NMSCs) but for the treatment of the thicker nodular basal cell carcinoma (nBCC) enhanced penetration of the prodrug is required. This study employed a new higher pressure, oxygen pressure injection (OPI) device, at the time of Metvix® application with a view to enhancing the penetration of MAL into the tumors. Each patient had Metvix® applied to a single nBCC followed by application of a higher pressure OPI device. Following different time intervals (0, 30, 60, 120 or 180 min) the tumors were excised. The maximum depth and area of MAL penetration achieved in each lesion was measured using PpIX fluorescence microscopy. As expected, an increase in the depth of MAL-induced PpIX accumulation and area of tumor sensitized was observed over time; when the Metvix® cream was applied for 0, 30, 60, 120 and 180 min the median depth of PpIX fluorescence was 0%, 21%, 26.5%, 75.5% and 90%, respectively and the median area of tumor sensitized was 0%, 4%, 6%, 19% and 60%, respectively. As the investigation presented here did not include a control arm, the relative depths of fluorescence observed in this study were statistically compared (using the non-parametric Mann Whitney U test) with the results of our previous study where patients had Metvix® cream applied either with or without the standard pressure OPI device. When the higher pressure OPI device was employed compared to without OPI this increase was observed to be greater following 30, 120, and 180 min although overall not significantly (p=0.835). In addition, no significant difference between the higher pressure OPI device employed here and the previously investigated standard pressure OPI device was observed (p=0.403). However, when the results for both OPI devices were combined and compared to the standard treatment (no OPI employed) group, although the difference did not reach significance (p=0.531) a consistent and substantial increase in the depth of PpIX fluorescence was observed, therefore employment of an OPI device during topical MAL-PDT protocols warrants further investigation as a technique for enhancing MAL penetration