The Astros called up lefthanded pitcher Brett Oberholtzer from Class AAA Oklahoma City and sent down righthander Hector Ambriz Tuesday afternoon. Oberholtzer posted a 5-6 record with a 4.60 ERA in 15 starts with the Redhawks. He appeared in one game for the Astros this season, a 5-4 loss to the Indians on April 21. In 39 relief appearances with the Astros, Ambriz had an 5.40 ERA and collected two saves.
