Biotech minnow Vernalis jumped 20 1/2p to 52 1/2p after announcing that its frovatriptan anti-migraine treatment helps to prevent menstrually associated headaches. Provalis, the maker of medical machines and diagnostic products, edged up 1p to 8 1/2p. The first- quarter has started well with healthy sales and orders. Osmetech, the developer of electronic odour sensors, nosedived 2 1/4p to 2 3/4p. It is raising £5.43m via a placing at 2p to help provide fresh working capital.