The Astros purchased the contract of relief pitcher Hector Ambriz Wednesday while designating Armando Galarraga for assignment.

Ambriz, who opened the 2012 season with the Cleveland organization before signing with the Astros in June, has allowed 22 earned runs in 57.1 innings for a 3.45 ERA at the Triple-A level this season.

Galarraga, who is best known for his near-perfect game in 2010, was 0-4 with a 6.75 ERA in five starts with the Astros in 2012.

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