Tokyo stocks were mixed Wednesday morning, weighed down by concerns over the adverse impact on equities of rising U.S. long-term interest rates, but the downside was supported by a weaker yen boosting exporters. The 225-issue Nikkei Stock Average fell 111.15 points, or 0.29 percent, from Tuesday to 38,300.81. The broader Topix index was up 0.16 point, or 0.01 percent, at 2,651.63. The U.S. dollar rose to the upper 151 yen range in Tokyo as the upward trend of U.S. long-term interest rates amid recent solid economic data raised the prospect that the interest differential between Japan and the U…