HOUSTON -- The Astros have invited 35 to 40 players to a pre-Draft workout at Minute Maid Park following Thursday's game against the Nationals. The Astros have four of the first 58 picks and five of the first 90 in the 2010 First-Year Player Draft, which begins Monday in Secaucus, N.J.

The regional supervisors -- Clarence Johns, Ralph Bratton and Mark Ross -- and southern California area scout Tim Costic have been meeting this week to go over the three different draft boards the Astros have pieced together at Union Station.

"Now it's a case of merging those lists and hopefully getting ready to take advantage of four of the first 58 picks in the Draft," general manager Ed Wade said.

Assistant general manager Bobby Heck and national cross checker David Post have been going over potential Draft picks, position-by-position, to ensure they're on the same page. The three Draft boards are broken down by West, Central and East regions, and they'll be merged with the top 100 players making it onto the main board.

Oswalt unaware of list of teams for trade

HOUSTON -- Astros pitcher Roy Oswalt, who's been the subject of numerous rumors and admitted last month he had requested a trade to a contender, said Wednesday he's not aware of a list of teams to which he would approve a trade.

Oswalt, whose contract expires at the end of the 2011 season, has a full no-trade clause and would have to approve any trade from the Astros. General manager Ed Wade doesn't discuss trades, but acknowledged last month Oswalt's agent had asked for a trade.

The Astros aren't believed to be actively shopping Oswalt, and a trade would be challenging considering Oswalt's desire to play for a contender, the large amount of money remaining on his contract and the caliber of prospects the Astros would likely want in return.

Oswalt is 3-7 with a 2.78 ERA in 11 starts this year. He began the season with 10 consecutive quality starts before being ejected in the third inning of Monday's game against the Nationals for what was deemed showing up an umpire.

Clark to manage in Dominican Winter League

HOUSTON -- Astros third-base coach Dave Clark has been named manager of the Licey Tigers club for the Dominican Winter League season, general manager Ed Wade announced Wednesday. Clark, who served as Astros interim manager for the final 13 games of the 2009 season, has managed six seasons in the Minor Leagues and one season in the Hawaiian Winter League.

"I've been talking to the organization for a couple of years about doing it," Clark said. "We have a Dominican scout down there, and he's been my contact guy and looking out for me and something came through. I met with the guys in Spring Training, and they were telling me they wanted to me to be one of the guys. There was a panel of four guys, which included myself, and last week they called and said, they wanted me to manage."

During his six seasons (2003-08) as a Minor League manager, Clark won two league titles and twice was named Manager of the Year, first in '03 after guiding Class A Advanced Lynchburg to the Carolina League finals, and then in '06 after leading the Astros' Double-A Corpus Christi Hooks club to the Texas League championship.

He also won a league title in 2004, guiding the Class A Hickory Crawdads to the South Atlantic League championship. Clark managed four seasons in the Astros' system, spending three seasons at Corpus Christi ('05-07) before moving up to Triple-A Round Rock in '08. He became third-base coach for the Major League club in '09.

"We're extremely pleased that Clarkie was selected for the Licey job," Wade commented. "This is another stop on Dave's way to a tremendous Major League managerial career. We know his opportunity is on the near horizon, and working in the highly-competitive Dominican Winter League environment will further accentuate his qualifications."

Sampson gets another cortisone shot

HOUSTON -- Right-hander Chris Sampson was scheduled to get a second cortisone shot in his right shoulder Wednesday. He was placed on the disabled list Tuesday with right rotator cuff tendinitis and underwent an MRI and was diagnosed with subacromial bursitis in his right shoulder.

Sampson was supposed to receive two cortisone shots Tuesday, but he battled migraines all day and was vomiting. He was feeling much better upon his arrival at the ballpark Wednesday, but said he'll need three to five days for the cortisone to work to its full extent.

"I've got to rest it, and let the inflammation get out of there and let the cortisone take over and get to work and stay positive and rest it," Sampson said. "Hopefully we can get back to where we were."

Sampson posted a 1.50 ERA in his first 19 games of the season, but he had allowed 12 hits and 11 earned runs in two innings in his next three outings while battling the shoulder injury.

"It had quite a bit to do with it," Sampson said. "It wasn't letting me finish pitches. No matter how hard I tried to battle through it, it was affecting me. I had to get something done and see exactly what it was and what was causing it, and thank goodness we found it and got the cortisone and we can get back to where we were."

Sampson, who was on the disabled list last year with right shoulder spasms, said he learned from former teammate Doug Brocail last year to not pitch through pain.

"It's hard because we're all competitors, and we all want to take the ball, but it was getting to the point [where] I wasn't doing myself or the team any favors," Sampson said. "I decided to speak up and try to get it better."