Tokyo stocks were mixed in early trading Thursday, as buying boosted by U.S. data showing cooling inflation was offset by selling of exporter issues on the back of a stronger yen. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 223.19 points, or 0.57 percent, from Wednesday to 39,099.90. The broader Topix index was down 2.54 points, or 0.09 percent, at 2,753.90. On the top-tier Prime Market, gainers were led by machinery, service, and oil and coal product shares. The main decliners were insurance, electric power and gas, and marine transportation shares. At 9 a.m., …