The T1799A point mutation is present in posterior uveal melanoma

An activating mutation in exon 15 of the BRAF gene is present in a high proportion of cutaneous pigmented lesions. Until recently this mutation had however only been identified in one case of posterior uveal melanoma. Despite this apparent lack of the BRAF mutation, inappropriate downstream activation of the Ras/Raf/MAPK pathway has been described in posterior uveal melanoma. Based on the already recognised morphological and cytogenetic heterogeneity in uveal melanoma, we hypothesised that the BRAF mutation may be present in uveal melanoma but only in some of the tumour cells. In this study, we analysed 20 ciliary body and 30 choroidal melanomas using a nested PCR-based technique resulting in the amplification of a nested product only if the mutation was present. This sensitive technique can identify mutated DNA in the presence of wild-type DNA. The mutation was identified in 4 of 20 (20%) ciliary body and 11 of 30 (40%) choroidal melanomas. Further analysis of separate areas within the same choroidal melanoma demonstrated that the mutation was not present in the entire tumour. In conclusion, the T1799A BRAF mutation is present in a proportion of posterior uveal melanomas but within these tumours the distribution of the mutation is heterogeneous

Reconceptualising PCK research in D&T education: proposing a methodological framework to investigate enacted practice

Since first conceived, the concept of pedagogical content knowledge (PCK) has attracted much attention. Despite being lauded by educationalists as the unique knowledge base of teachers, research on the concept over the past 30 years has yet to result in a universally accepted definition being presented. Much of the contentions surrounding the lack of an agreed upon conception appear to have stemmed from difficulties in understanding the relationship between PCK, other areas of teacher knowledge, teacher beliefs, and enacted practice. This paper considers the application of PCK frameworks to design and technology (D&T) education, through an analysis of the nature of the discipline from an ontological and epistemological perspective and contemporary perspectives on the construct of PCK. It is theorised that the volition afforded to teachers in D&T through weakly framed subject boundaries negates the effective application of PCK frameworks, as teachers’ beliefs have a greater impact on enacted practices. In an attempt to better understanding enacted practice in D&T education, the paper proposes a methodological framework centred on the interactions between teachers’ beliefs and knowledge in the discipline, through synthesising the concept of amplifiers and filters of practice with the nature of D&T education. The proposed framework outlines the need to recognise individual teachers’ conception of capability as a critical influence on enacted practice