7/6 Extra bases

Ryan Dempster played catch Wednesday and will try to throw a side session on Thursday. If all goes well, he could be inserted into the rotation on Saturday against the Pirates for one more start before the All-Star break. The right-hander missed his scheduled start Monday because of discomfort in his stomach and core.

* Carlos Zambrano threw a side session Wednesday at Wrigley Field. Mike Quade’s younger brother, Scott, was his catcher. Zambrano is on the DL with lower back soreness.

“If he has a healthy side today, then all systems are go for him to throw a simulated game to do something to be ready to come off the break and be ready to go,” Quade said.

* Starlin Castro is keeping tabs on All-Star shortstops Jose Reyes and Troy Tulowitzki. Both have been injured, which means the Cubs shortstop may get lots of playing time in Tuesday’s All-Star Game in Phoenix.

* Jeff Baker, who had to come out of Tuesday’s game because of back spasms, did not take part in batting practice on Wednesday and remained day to day.

* Andrew Cashner, on the DL since April 6, one day after his first and only start of the season, was to throw Monday in Mesa, Ariz. Cashner was on the trip to continue his rehab from a strained right rotator cuff.

* Illinois Sen. Dick Durbin was on the field before the game. One of his staffers is a nephew of Cubs pitcher Rick Reuschel.

– Carrie Muskat