The simmering stand-off between the Texas Racing Commission and the powers behind the Horseracing Integrity and Safety Act (HISA) bubbled higher Monday, when the commission's executive director issued a letter warning Texas will prohibit the import and export of pari-mutuel simulcast signals at its racetracks if the Act goes into effect on July 1 with jurisdictional authority over the state's Thoroughbred racing operations. In the letter, Amy Cook, the Texas Racing Commission's executive director, invokes various statutes in the Interstate Horseracing Act, the Texas Racing Act and the Texas Rules...