With Altoona this season, Nannini was 1-1 with a 4.95 ERA in 14 appearances spanning 20 innings. The right-hander struck out 19 and walked five, making one appearance with Triple-A Indianapolis.
Nannini was with the Cubs for a brief stay once before. He was acquired along with LHP Russ Rohlicek from Houston in 2002 as part of a trade that sent reliever Flash Gordon to the Astros.
Entering 2007, Nannini had a combined record of 76-61, with a 4.02 career ERA in nine minor league seasons. He was a first-round draft pick by the Astros in 1998.
Additionally, the Cubs signed INF/OF John Nelson and assigned him to Triple-A. Nelson, 28, previously spent time with Triple-A Memphis, batting .162 in 47 games earlier this season. Five of his 17 hits with Memphis were home runs.
A season ago, Nelson hit .215 with 21 home runs and 48 RBIs in 125 games with Memphis and made his major league debut with St. Louis.
Nelson entered 2007 a career .247 hitter in six minor league seasons with the Cardinals. He was an eighth-round Cardinals draft pick in 2001.