Shares of

Sybron Dental Specialties

( SYD) were among the best-performing health-related stocks Wednesday, jumping 12% after the dental-products company agreed to be acquired by

Danaher

(DHR) - Get Report

for about $2 billion in cash.

Sybron holders will receive $47 a share, a 13% premium over Tuesday's closing price of $41.74. Danaher, which makes professional instruments and tools, also expects to assume about $200 million in debt. "The combination of Danaher and Sybron Dental makes very strong strategic and financial sense," Danaher said in a statement. "Sybron's consumables and small-equipment offering are a logical extension of Danaher's existing dental-equipment portfolio and will allow us to more broadly serve the dental community."

Sybron posted sales of about $650 million during its most recently completed year. Sybron shares were trading up $5.13 to $46.87, while Danaher shares advanced 75 cents, or 1.2%, to $66.10.

Discovery Partners International

(DPII)

rose 9% after the company said that it plans to merge with privately held Infinity Pharmaceuticals. The company, which will be called Infinity Pharmaceuticals when the deal closes, will focus on cancer drug discovery and development. Infinity shareholders will own about 69% of the company after the deal closes, while Discovery Partners shareholders will own the rest.

"After an extensive review of potential merger candidates and their product pipelines, Discovery Partners identified Infinity Pharmaceuticals as an organization with the potential to create significant value for our shareholders," Discovery said. The deal is expected to close during the third quarter. Shares of Discovery Partners were trading up 22 cents to $2.63.

Shares of

Vanda Pharmaceuticals

(VNDA) - Get Report

fell 8% on the company's first day of trading as a public company. The biopharmaceutical concern's initial public offering priced 5.75 million shares at $10 apiece, below an earlier projected range of $12 to $14.

The company, which is developing products for central nervous-system disorders, plans to use proceeds from the $57.5 million offering to fund several clinical trials and for general purposes. J.P. Morgan Securities and Banc of America Securities led the underwriting syndicate. Shares recently were down 75 cents to $9.25.

Shares of

Targacept

(TRGT)

, another biopharmaceutical IPO, also were lower on their first trading day. The 5 million-share IPO priced at $9 a share, below the expected range of $11 to $13.

The company, which also is developing treatments for central nervous system diseases, plans to use the proceeds to fund clinical trials, preclinical testing, research and development activities and other business expenses. Shares were trading down 50 cents, or 5.6%, to $8.50.

Genentech

( DNA) shares were down about 2% after the biotech behemoth's first-quarter report. The company earned $421 million, or 39 cents a share, on operating revenue of $1.99 billion. Excluding items, Genentech earned $491 million, or 46 cents a share.

Analysts surveyed by Thomson First Call expected earnings of 41 cents a share, before items, on revenue of $1.97 billion. During the year-earlier quarter, the company earned $284 million, or 27 cents a share, on revenue of $1.46 billion. Excluding items, year-earlier earnings were $312 million, or 29 cents a share.

Looking ahead, Genentech now sees 2006 earnings growth of 45% to 55%, implying earnings of $1.86 to $1.98 a share when compared with 2005 earnings of $1.28 a share. Previously, the company forecast earnings growth of 40% to 50%, or earnings per share of $1.79 to $1.92. Analysts project earnings of $1.86 a share. Shares were trading down $1.35 to $80.35.

Other health care volume movers included

Boston Scientific

(BSX) - Get Report

, up 52 cents to $21.88;

Pfizer

(PFE) - Get Report

, up 8 cents to $24.43;

Bausch & Lomb

( BOL), down $2.66 to $46.37;

UnitedHealth Group

(UNH) - Get Report

, up $1.76 to $53.31;

Novavax

(NVAX) - Get Report

, up 63 cents to $5.44;

Amgen

(AMGN) - Get Report

, down 50 cents to $69.74;

Merck

(MRK) - Get Report

, down 26 cents to $33.80;

Johnson & Johnson

(JNJ) - Get Report

, up 12 cents to $57.87;

Generex Biotechnology

(GNBT)

, up 13 cents to $2.65;

Bristol-Myers Squibb

(BMY) - Get Report

, down 2 cents to $24.14; and

Schering-Plough

( SGP), down 2 cents to $18.43.