Continuing its post-Hurricane Katrina strategy of aggressive expansion, Ochsner Health Systems has reached a deal to buy NorthShore Regional Medical Center and the adjacent ambulatory surgery center in Slidell, LA. The move, struck via an undisclosed purchase agreement with California real-estate trust HCP Inc. and Tenet Healthcare Corp. of Texas, will give Ochsner its eighth hospital in the state and first on the north shore, the New Orleans Times Picayune reports.