Shares of

NitroMed

( NTMD) were among the worst-performing health-related stocks Tuesday, plunging 32% after the drugmaker posted disappointing first-quarter results.

The company reported a loss of $25.9 million, or 75 cents a share, on revenue of $2.3 million. Analysts polled by Thomson First Call expected a smaller loss of 68 cents a share on revenue of $5 million. A year earlier, the company reported a loss of $19.6 million, or 65 cents a share, on revenue of $398,000.

Looking ahead, NitroMed sees 2006 product sales of about $20 million. Analysts project sales of $44.4 million. Shares were trading down $2.75 to $5.86.

Vical

(VICL)

soared 31% after the company reported a better-than-expected first quarter and gave positive early-stage study results of a bird flu vaccine. For the first quarter, the drug developer reported a loss of $4.5 million, or 16 cents a share, on revenue of $5.6 million. Analysts expected a wider loss of 22 cents a share, with revenue of $3.7 million. Last year, the company posted a first-quarter loss of $7.6 million, or 32 cents a share, on revenue of $2.7 million. For 2006, Vical continues to forecast an adjusted loss of $22 million to $26 million.

Separately, the company said its three-component flu vaccine candidate provided 100% protection in mice and ferrets against lethal doses of the H5N1 avian flu virus. Mice and ferrets that did not receive the vaccine did not survive. "Based on the results, the company is continuing to advance toward human testing of the pandemic flu DNA vaccine candidate," Vical said. Shares recently had jumped $1.68 to $7.18.

Shares of

ev3

( EVVV) slid 10% after the medical-device company posted mixed first-quarter results and lowered its 2006 sales guidance. The company posted a loss of $24.5 million, or 44 cents a share, narrowed from $28.1 million, or $10.76 a share, a year earlier, when there were far fewer shares outstanding. Excluding items, the company reported a loss of $17.1 million, or 31 cents a share, a penny better than Wall Street's projection. Revenue rose to $42.2 million from $27.7 million, but missed analysts' expectation of $43.5 million.

Looking ahead, ev3 now sees 2006 sales of $196 million to $208 million, down from an earlier view of $200 million to $220 million. The company blamed the revision on unexpected FDA product-clearance delays. For the second quarter, the company sees sales of $45 million to $49 million. Analysts project second-quarter sales of $49.6 million and full-year sales of $208.6 million. Shares were trading down $1.62 to $13.95.

Cyberonics

(CYBX)

jumped 13% after the medical-device maker boosted its fourth-quarter sales outlook. The company now sees sales about $36 million, up from an earlier forecast of $34 million. "Record sales combined with improvements in productivity and efficiencies in all departments are expected to have a significant positive impact on the fourth quarter net loss that will be reported in late May," the company said. Analysts project revenue of $33.7 million and a loss of 34 cents a share. Shares were up $2.98 to $25.36.

Shares of

United Therapeutics

(UTHR) - Get Report

fell 9% after the drugmaker's first-quarter results missed expectations. The company earned $2.3 million, or 10 cents a share, on revenue of $33.2 million. Excluding items, the company earned $10 million, or 39 cents a share. Analysts expected earnings of 50 cents a share, before items, on revenue of $34.4 million. During the year-earlier quarter, the company earned $7.7 million, or 31 cents a share, on revenue of $23.2 million. Shares were down $5.37 to $56.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 14 cents to $25.26;

UnitedHealth Group

(UNH) - Get Report

, down $1.02 to $48.78;

Generex Biotechnology

(GNBT)

, down 8 cents to $3.02;

Boston Scientific

(BSX) - Get Report

, down 10 cents to $22.18;

Aetna

(AET)

, down 36 cents to $39.39;

Amgen

(AMGN) - Get Report

, down $1 to $65.86;

Medtronic

(MDT) - Get Report

, down 56 cents to $49.39;

Bristol-Myers Squibb

(BMY) - Get Report

, down 7 cents to $24.93;

Johnson & Johnson

(JNJ) - Get Report

, up 11 cents to $58.70;

Schering-Plough

( SGP), up 8 cents to $19.13.