Yankee Doodle, America is calling. Aberdeen Asset Management (ADN) has stepped up its expansion in North America with the £112 million acquisition of Artio Global Investors, sending its shares up 2.7% to 427.4p. It is also buying a stake in SVG Advisers for £17.5 million. Artio, which as a net asset value £90 million, deepens Aberdeen's distribution network in the region while adding to its fixed income capabilities. Chief executive officer Martin Gilbert (pictured) says North America is a key growth market for Abderdeen.

Yet analysts at RBC Capital Markets note that Artio has been in crisis for years and does not match Aberdeen's stated strategy of targeting quality businesses. They also believe these deals will limit returns to shareholders.

Avocet Mining (ABM) slumped 41% to 30.5p after saying up to half the gold in its West African miner may no longer be economical to mine. This throws up problems with future cash flow, so it needs to raise a massive amount of money to buy out a loan agreement (called a 'hedge'). Click here for the full story.

The prayers of the 30 million men suffering from premature ejaculation in Europe could be answered after Plethora Solutions? (PLE:AIM) announced that it is in advanced discussions to secure new money to fund to approval its treatment for the condition. Its shares jumped 29% to 1.75p.

Also announcing positive news was Kea Petroleum (KEA:AIM), which gained 28% to 9.62p after it confirmed that it has made a new oil discovery in New Zealand. The oil and gas company made the find in a new sand reservoir at Puka 2 in the lower Mount Messenger Sands. Management claim the porosity and permeability values are amongst the highest recorded in Mount Messenger?s reservoirs and as such Kea expects to record higher oil flow rates than those recorded at its Puka 1 project.

Shares in industrial chain maker Renold (RNO) dropped 24% to 21.5p after the group issued its third profit warning in the space of seven months. Click here for the full story.

Meanwhile, adjusted pre-tax profits plunging 22% to £1.1 million were not enough to dampen enthusiasm for media company Electric Word (ELE:AIM). Its shares jumped almost 10% to 2.05p following the release of its preliminary results for the year to December, which were in-line with expectations.

News on an oilfield in Columbia sent Gold Oil (GOO:AIM) up more than 6% to 1.88p. The oil and gas exploration company has increased its interest in the Nancy Burdine field in Columbia to full ownership, up from 81%. Management will now focus on optimising production, establishing sufficient accounting procedures and extending the field.

Securing 510(k) clearance from the US Food and Drug Administration (FDA) to market a new hydrogel formulation of its Vashe technology in the US was enough to push PuriCore (PURI) up 7.2% to 44.5p. The new Vashe Skin & Wound Hydrogel relieves pain, burning, and itching experienced with conditions, such as atopic dermatitis. Management at the water-based clean technology company intend to use the approval to develop products in dermatology, wound care, and animal health, estimating that these markets can generate sales of $30 million in the US.

South American gold producer Orosur Mining (OMI:AIM) ended a long share price decline by announcing that its Arenal Deep development ramp has been completed. The market liked the progress report, sending the shares up 7.5% to 34p. The completion of the project will enable Orosur to offset higher expected costs from the surface operations at San Gregorio in 2014, analysts at Seymour Pierce said in a research note claiming that a re-rating could be on the way.

Poor trading in some of its divisions led Tristel (TSTL:AIM), a manufacturer of infection prevention, contamination control and hygiene products, to fall more than 16% to 24.50p. A trading update for the six months to January highlights a deeper-than-expected decline in its endoscopy business. Management do not believe it will not recover to the anticipated levels and now see a lower level of endoscopy revenues this year resulting in a £600,000 loss. Analysts at Finncap believe the company will exit its multi-channelled endoscopy business.

Also falling is shower-maker Norcros (NXR), down 6.7% to 15.63p. A trading statement spoke of challenging conditions in its South African business. However, in the 18 weeks to February 3 the Wilmslow-based company saw growth in its UK business where revenues increased 9.5% year-on-year.

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Issue Date: 14 Feb 2013