Menthol reduces phototoxicity pain in a mouse model of photodynamic therapy.

Phototoxicity-induced pain is a major clinical problem triggered by light acting on photosensitising drugs or endogenous porphyrins, notably protoporphyrin IX (PpIX), an intermediary in heme biosynthesis. Protoporphyrin IX accumulates in individuals with erythropoietic protoporphyria and is elevated during photodynamic therapy subsequent to application of 5-aminolevulinic acid (ALA). Pain occurs during irradiation of PpIX and responds poorly to conventional analgesics. Our objective was to develop a model of PpIX phototoxicity pain and investigate the potential of menthol as an analgesic. Application of ALA to the tails of C57 black and SWISS white mice caused PpIX accumulation and nociception during irradiation (630 nm at 3.7 J/cm). Despite similar PpIX accumulation, C57 mice exhibited less pain behavior compared with SWISS mice because of light absorption by pigmentation. Irradiation of ALA-treated dorsal root ganglion neurons caused phototoxicity-evoked action potentials (APs) in both mouse strains. The antioxidant L-tryptophan increased the light dose required to elicit such APs. By contrast, the addition of keratinocytes to neuronal cultures decreased the threshold for APs, suggesting a requirement for proliferating cells. Inhibition of fatty acid amide hydrolase, selective antagonism of TRPV1 or the application of lidocaine or its quaternary derivative QX-314, reduced AP frequency, whereas antagonism of TRPA1 had no effect. These results suggest that products of singlet oxygen-mediated lipid peroxidation trigger nociceptor activation via TRPV1. Menthol inhibited phototoxicity-evoked APs and reduced pain behavior when applied topically to mice. These findings suggest that menthol might provide pain relief in patients experiencing PpIX-phototoxicity pain caused by photodynamic therapy or erythropoietic protoporphyria.

The value of mentorship in medical education.

BACKGROUND: The transition from senior medical student to working safely and effectively as a new junior doctor is one of the biggest challenges that a new graduate will face. In 2014 the General Medical Council published The state of medical education and practice in the UK, reporting that some new doctors continue to struggle with increased responsibilities. We classify these instances as a 'performance gap', describing occasions in clinical practice where an individual exceeds their performance capacity. The Medical Mentorship Programme addressed identified performance gaps through a structured curriculum of simulation-based education and facilitated clinical practice. METHODS: Programme content was based on the experiences of the authors and their peers in graduating from their undergraduate training programme and becoming junior doctors. A questionnaire was disseminated to junior doctors in their first clinical rotation. The questionnaire asked doctors to describe instances where they experienced a performance gap. These data informed the development of the Medical Mentorship Programme. The effect of this programme was then evaluated via focus group discussion. RESULTS: The Medical Mentorship Programme has been shown to be an effective conduit for supporting the transfer of learning needed to address performance gaps in students. The programme increased the confidence of students in preparation for clinical practice and allowed junior doctors to reflect on their professional development. The programme combined complementary teaching techniques - mentorship, simulation and direct clinical experience - to aid the professional development of both students and mentors. Some new doctors continue to struggle with increased responsibilities.