The S&P/ASX 200 Index (ASX: XJO) is back on form and charging higher on Thursday. In afternoon trade, the benchmark index is up 0.8% to 8,607.4 points.

Four ASX shares that are rising more than most today are listed below. Here's why they are climbing:

Evolution Mining Ltd (ASX: EVN)

The Evolution Mining share price is up 4% to $7.58. This follows a rebound in the gold sector on Thursday after a selloff yesterday. It isn't just Evolution Mining that is rising today. A number of ASX gold shares are climbing with it. This has led to the S&P/ASX All Ords Gold index rising 2.4% at the time of writing.

Orthocell Ltd (ASX: OCC)

The Orthocell share price is up 4% to $1.27. This morning, this regenerative medicine company announced the first sales of its Remplir product in the United States market. Remplir, which was recently approved by the US FDA, is a collagen wrap used in nerve repair surgery to improve regeneration of damaged nerves and patient outcomes. Orthocell's CEO and managing director, Paul Anderson, said: "Translating Remplir's regulatory clearance in the US to first sales revenue in a little over three months is a testament to the hard work we've done with our US roll out plan. This covers everything from our key internal hires in sales, marketing and medical affairs, appointing specialist distributors, Australian manufacturing ramp up and working with our on-the-ground US logistics partner."

Platinum Asset Management Ltd (ASX: PTM)

The Platinum share price is up over 12% to 55.75 cents. This appears to have been driven by a broker note out of Bell Potter this morning. According to the note, the broker has upgraded the fund manager's shares to a buy rating with a 60 cents price target. Following news that it plans to merge with L1 Capital, the broker said: "Overall, we believe this is a very good deal for PTM. Firstly, the momentum in the L1 business means the combined business should be growing, particularly as we had previously assumed that PTM would continue to fade."

Turaco Gold Ltd (ASX: TCG)

The Turaco Gold share price is up over 5% to 49 cents. This follows news that the gold explorer has found high-grade gold during recent drilling at the Afema project in the Cote d'Ivoire. Managing Director, Justin Tremain, commented: "These latest results are significant in that they clearly demonstrate additional gold bearing structures outside the 1.6Moz Woulo Woulo deposit and with potential for higher grades. Auger drilling has extended the scale at both Herman and Baffia and has generated well defined targets with drilling underway."