We have used microarray gene expression profiling and machine learning to predict the presence of BRAF mutations in a panel of 61 melanoma cell lines. The BRAF gene was found to be mutated in 42 samples (69%) and intragenic mutations of the NRAS gene were detected in seven samples (11%). No cell line carried mutations of both genes. Using support vector machines, we have built a classifier that differentiates between melanoma cell lines based on BRAF mutation status. As few as 83 genes are able to discriminate between BRAF mutant and BRAF wild-type samples with clear separation observed using hierarchical clustering. Multidimensional scaling was used to visualize the relationship between a BRAF mutation signature and that of a generalized mitogen-activated protein kinase (MAPK) activation (either BRAF or NRAS mutation) in the context of the discriminating gene list. We observed that samples carrying NRAS mutations lie somewhere between those with or without BRAF mutations. These observations suggest that there are gene-specific mutation signals in addition to a common MAPK activation that result from the pleiotropic effects of either BRAF or NRAS on other signaling pathways, leading to measurably different transcriptional changes.

Tryptamine acts as a precursor of the indole alkaloids in Vinca rosea. Secologanin (1) condenses with tryptamine to yield vincoside (2) and isovincoside (5). the absolute configuration of these products is determined and their chemistry is explored. It is demonstrated by single-and double-labelling experiments that vincoside is the precursor of representative indole alkaloids from the Corynanthe, Aspidosperma, and lboga families in Vinca rosea ; isovincoside is not involved in these biosyntheses. Vinca rosea plants are shown to contain vincoside, isovincoside, and N-acetylvincoside by a combination of radiochemical dilution analysis and direct isolation. [5-3H] -Loganin fed to Vinca rosea is incorporated efficiently into vincoside and isovincoside.The steps are discussed by which vincoside is converted into the three types of indole alkaloids and it is proved that the side-chain unsaturation of vincoside is essential for operation of the later biosynthetic stages. The main part of this work has been briefly r e p~r t e d .~,~ 4 A. R. Battersby, P w e and Appl.

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Cationic ruthenium(II) pentamethylcyclopentadienyl benzenesulfonamide sandwich complexes have been synthesized and screened for enzymatic inhibition of the physiologically dominant carbonic anhydrase (CA) isozymes: human CA I and II, mitochondrial isozymes VA and VB, and the cancer-associated isozyme IX. The complexes demonstrated weaker binding to CAs compared with typical aromatic sulfonamides, inhibiting the enzyme at high nanomolar concentrations. An in vitro cytotoxic evaluation of the complexes was also undertaken against a range of tumorigenic cell lines and a healthy human cell line. Complexes inhibited the growth of cancerous cells at low micromolar concentrations while expressing lower levels of toxicity towards the normal human cell line. Factors influencing the synthesis, cytotoxicity, and enzyme affinity for this series of organometallic complexes are discussed.

Objective: To determine the value of shade in protecting humans from solar ultraviolet (UV) radiation.Design and setting: Measurement with photometers of protection factors for ultraviolet B radiation (UVB) and for total solar radiation for different types of trees and other structures during the summer months (1995)(1996)(1997) in south-east Queensland. (The protection ratio is the ratio of the intensity of UVB or total solar radiation in direct sunlight to that in shade.)Results: For summer sun at midday, the mean (SD) UV protection ratio for the shade of trees (n =65) was 4.21 (1.36) on a horizontal surface and 1.33 (0.30) on a vertical surface. In contrast, the mean (SD) protection ratio for total solar energy (primarily infrared) was much higher (12.1 [1.4]). Trees common in recreational areas in Australia (eucalypts: UV protection ratio, 3.52 [0.79]; Norfolk Island pines: UV protection ratio, 3.72 [0.98]) offered reduced protection compared with trees with more dense foliage (UV protection ratio, 5.48 [1.44]). Over a whole day, measurement of shade by trees and other structures showed that the UV protection ratio was lower in the morning and afternoon. Shade from awnings, buildings and hats gave similar results to those for trees. Both at midday and over a whole day satisfactory protection (UV protection ratio> 15) was obtained only in shade which eliminated exposure to the sky as well as to direct sunlight; for example, in thickly wooded areas and under low, widely overhanging structures.Conclusions: Most forms of shade, while useful, offer people insufficient protection from solar UV. A fair-skinned person sheltering under a tree could suffer sunburn after less than one hour. There is a need for appropriate design of structural shade, use of other solar protection measures in conjunction with shade, and research on behavioural responses to shade.