Boston Scientific ( BSX) rose 3% to $17.23 after the company said 5,000 patients have now been treated with its Precision Spinal Cord Stimulation System, a rechargeable shocking device to treat chronic pain. The company is slated to report its quarterly earnings on Thursday.

Bovie Medical's ( BVX) shares gained ground after the company announced it received Food and Drug Administration marketing approval for a suture-removal device for human, as well as animal, medical procedures. Shares were up 3.8% to $8.50.

Shares of DOV Pharmaceutical ( DOVP) rose on positive results of an early trial on its experimental painkiller bicifadine. The drug didn't show signals of possibly causing cancer in rats or mice over two years. "This timeframe is accepted as analogous to administering the drug over a lifetime in humans," the company said in a press release. Shares of DOV were up 4.3% to $1.96.

Alnylam Pharmaceuticals' ( ALNY) shares fell 1.6% to $12.40 after the company reported a wider-than-expected net loss in the second quarter.

The company lost $9.9 million, or 31 cents a share in the quarter, including $1.6 million, or 5 cents a share, in stock-based compensation expenses, compared with a loss of $11.1 million, or 54 cents a share, a year ago. Analysts were expecting the company to lose 28 cents a share. Revenue in the second quarter exceeded expectations, reaching $6 million vs. analysts' estimates of $5.6 million.

Aspect Medical Systems ( ASPM), a maker of anesthesia-monitoring systems, sank 14.9% to $15.66, despite better-than-expected earnings in the second quarter. The company earned $2.1 million, or 9 cents a share, compared with $1.6 million, or 7 cents a share, last year.

Excluding stock-based compensation expenses, the company earned 16 cents a share, compared with analysts' expectations of 14 cents. Aspect's sales were up 21% to $22.6 million in the quarter.

The company's third-quarter guidance was lower than analysts were expecting, however. In its earnings report, the company said it expects to earn 14 cents to 16 cents a share on sales of $22 million to $22.8 million. Analysts surveyed by Thomson First call were expecting earnings of 16 cents a share in the third quarter on sales of $24.1 million.

Health-care education company Healthstream ( HSTM) fell despite its announcement that earnings and revenue rose in the second quarter. The company reported revenue of $8.2 million in the second quarter, up 21% from a year ago, and earnings of $289,000, or 1 cent a share. Last year, the company broke even. Shares were down 10.7% to $3.43.

Other health care companies on the move included MGI Pharma ( MOGN), down 1.2% to $15.06, and Edwards Lifesciences ( EW), off 1.3% to $42.71.

Affymetrix ( AFFX) was up 3.6% to $22.25, Hemispherx Biopharma ( HEB) rose 7.1% to $2.41, and YM BioSciences ( YMI) added 1% to $3.11.