GenVec

(GNVC)

shares jumped following an announcement that an experimental HIV vaccine created with the small biopharmaceutical company's technology has entered human clinical trials. The trials will be conducted at the vaccine research center of the National Institutes of Health in Bethesda, Md. and will study the safety and efficacy of the treatment in 15 patients with HIV. Shares were up 14.6% to $1.18.

Medical-technology company

Bruker BioSciences

(BRKR) - Get Report

sank following a downgrade by investment firm UBS. Biotech analyst Derik De Bruin downgraded the stock from a buy rating to neutral, saying the company is facing limited upside and increased competition from larger vendors of mass spectrometry technologies. De Bruin maintained his price target of $7. Shares fell 1.3% to $6.06.

Shares of

Omnicare

(OCR)

dropped after a downgrade from investment research firm Stifel Nicolaus. According to health care analyst Jerry Doctrow, who downgraded the stock from a buy to hold, despite an attractive valuation, "we are no longer comfortable recommending OCR because we believe lower pricing and legal settlements could erode some or all of the expected synergy we have been assuming in 2006 and 2007." Omnicare slumped 2.5% to $42.54.

Device maker

St. Jude Medical's

(STJ)

shares fell 2.5% to $36.04 despite the company's announcement that the Food and Drug Administration approved a new feature for its heart devices. The new feature, to be used in patients with a cardiac rhythm device or defibrillator implant, shows vital health data equivalent to what's provided in an echocardiogram within two minutes, compared with a test that usually takes between two hours and 30 minutes to conduct.

Among other health stocks on the move were

Neurobiological Technologies

(NTII)

, 3.3% lower to $2.63,

Nymox Pharmaceutical

(NYMX) - Get Report

, whose shares lost 3% to $2.55,

Bioprogress

(BPRG)

, down 13.7% to $7.76 and

Novacea

(NOVC)

, off 5.2% to $5.87.

SkyePharma

( SKYE) was up 2.6% to $4.74,

Praecis Pharmaceuticals

(PRCS)

gained 9.8% to $2.02,

AVI Biopharma

( AVII) jumped 19.3% to $4.27 and

AMN Healthcare Services

(AHS)

was up 4.6% to $23.03.