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Kerr A.C.,Photobiology Unit
Clinical and Experimental Dermatology | Year: 2011

The frequency, and thus availability to patients, of ultraviolet (UV) filters contained within sunscreens changes over time. Obtaining current data on filter availability is necessary when considering which agents to include in sunscreen series for patch and photopatch testing of patients. A survey of sunscreen products was undertaken in Dundee, UK, in 2010. In total, 337 products were identified, with a median sun-protection factor of 30 (range 2-50+). In these products, 19 UV filters were identified, of which the most common was butyl methoxydibenzoylmethane. Compared with data from 2005, most filters had an increase in frequency of inclusion, with a trend towards broader spectrum protection. This information should be of use to clinicians considering investigation of contact and photocontact allergy. It also aids determination of the allergenic potential of these filters when reports of allergy and photocontact allergy arise in the literature. © The Author(s). CED © 2011 British Association of Dermatologists.

Butler J.S.,University of Warwick | Woods J.A.,University of Warwick | Farrer N.J.,University of Warwick | Newton M.E.,Photobiology Unit | Sadler P.J.,University of Warwick
Journal of the American Chemical Society | Year: 2012

The octahedral PtIV complex trans,trans,trans-[Pt(N 3)2(OH)2(py)2] (1) is potently cytotoxic to cancer cells when irradiated with visible (blue) light. We show that the acute photocytotoxicity can be switched off by low doses (500 μM) of the amino acid l-tryptophan. EPR and NMR spectroscopic experiments using spin traps show that l-Trp quenches the formation of azidyl radicals, probably by acting as an electron donor. l-Trp is well-known as a mediator of electron transfer between distant electron acceptor/donor centers in proteins, and such properties may make the free amino acid clinically useful for controlling the activity of photochemotherapeutic azido PtIV drugs. Since previous work has demonstrated the ability of photoactivated 1 to platinate DNA, this suggests that the high potency of such photoactive platinum complexes is related to their dual attack on cancer cells by radicals and PtII photoproducts. © 2012 American Chemical Society.

Kerr A.,Photobiology Unit
Photodermatology, photoimmunology & photomedicine | Year: 2010

BACKGROUND: Photoallergic contact dermatitis (PACD) presents in patients after certain exogenous agents come into contact with the skin in the presence of ultraviolet and/or visible light. The best method currently available for investigating PACD is photopatch testing. However, photopatch testing as an investigation is under-used by clinicians, and therefore PACD may go undetected in many patients. PURPOSE: To highlight the importance of PACD and photopatch testing when investigating patients with a photo-exposed site dermatosis. METHOD: A comprehensive review of the available literature relating to PACD and photopatch testing. RESULTS: Experimental evidence suggests that PACD is a delayed type hypersensitivity reaction. Various agents have been historically shown to cause PACD, but currently the most common photosensitizers are sunscreens and topical non-steroidal anti-inflammatory drugs. Photopatch testing has in the past been subject to differing methodologies; however, a European consensus methodology now exists and should allow a greater comparison of results across centres. As chemical, pharmaceutical, and cosmetic industries produce new agents, photopatch testing of such agents in humans before release in the marketplace may prevent widespread contact with potent photosensitizers. It will also be important for ongoing multi-centre studies of existing agents to be conducted in order to keep the photopatch test batteries used by clinicians investigating PACD up to date.

Nie Z.,Photobiology Unit
Giornale Italiano di Dermatologia e Venereologia | Year: 2011

Keloid is a common skin condition, especially in people of Asian and African decent. The treatment of keloid is still unsatisfactory. Photodynamic therapy (PDT) is a novel treatment for this condition, but is widely used in treating certain skin pre-malignant and malignant lesions due to its high efficiency and safety. Another aspect of PDT is its scarless (or minimal scarring) wound healing after treatment despite the fact that it causes skin inflammation. There are a few independent reports that indicate 5-aminolevulinic acid (ALA) or methylaminolevulinate (MAL)-PDT may be effective in keloid and hypertrophic scars. The mechanism is largely unknown. PDT may exert these effects by acting on keratinocytes and fibroblasts or directly on collagen/extracellular matrix (ECM) in keloid tissues, by inducing keloid fibroblast apoptosis/necrosis, modulating growth factor and cytokine expression, reducing collagen/ECM synthesis and causing degeneration of formed collagen/ECM. These potential mechanisms and the scope for topical PDT of keloids are considered in this article.

Fenton L.,Photobiology Unit | Dawe R.,Photobiology Unit | Ibbotson S.,Photobiology Unit | Ferguson J.,Photobiology Unit | And 2 more authors.
British Journal of Dermatology | Year: 2014

Background Patients with lupus erythematosus (LE) are often abnormally photosensitive. Ultraviolet (UV) exposure can not only induce cutaneous lesions but may also contribute to systemic flares and disease progression. Various forms of energy-efficient lighting have been shown to emit UV radiation. Objectives To determine the effects of these emissions on individuals with LE. Methods This assessment investigated cutaneous responses to repeated exposures from three types of lighting: compact fluorescent lamp (CFL), light-emitting diode (LED) and energy-efficient halogen (EEH). The subjects were 15 patients with LE and a control group of five healthy volunteers. Results No cutaneous LE lesions were induced by any of the light sources. Delayed skin erythema was induced at the site of CFL irradiation in six of the 15 patients with LE and two of the five healthy subjects. Erythema was increased in severity and more persistent in patients with LE. One patient with LE produced a positive delayed erythema to the EEH. A single patient with LE produced immediate abnormal erythemal responses to the CFL, LED and EEH. Further investigation revealed that this patient also had solar urticaria. All other subjects had negative responses to LED exposure. Conclusions Compact fluorescent lamps emit UV that can induce skin erythema in both individuals with LE and healthy individuals when situated in close proximity. However, this occurs to a greater extent and is more persistent in patients with LE. EEHs emit UVA that can induce erythema in patients with LE. LEDs provide a safer alternative light source without risk of UV exposure. What's already known about this topic? Patients with lupus erythematosus (LE) can have abnormal cutaneous response to ultraviolet (UV) radiation. Compact fluorescent lamps (CFLs) emit UV that can exacerbate certain photodermatoses. UV-induced cutaneous response may lead to general disease progression including systemic activity. What does this study add? Skin erythema is induced by repeated CFL exposure in healthy individuals and those with LE. CFL-induced erythema is more persistent in individuals with LE. Light-emitting diodes offer a safe alternative light source for individuals with LE, without the risk of UV. © 2013 British Association of Dermatologists.

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