Shares of

Ciphergen Biosystems

(CIPH)

were among the worst-performing health-related stocks Tuesday, falling 23.6% after the company cut its first-quarter sales guidance.

The biotech company now expects sales of $6.3 million to $6.7 million, down from previous guidance of $8 million to $9 million. Analysts polled by Thomson First Call had been expecting sales of $8.5 million. The company also named Paul Smith VP of North American and European sales and said it will restructure its its sales programs. Ciphergen expects to post first-quarter results on May 6. Shares traded down 58 cents to $1.88.

PacifiCare Health Systems

(PHS)

rose 3.8% after the giant HMO said that its Secure Horizons Medicare Advantage plans will receive a rate increase of 6.5% to 7% beginning on Jan. 1, 2006. As a result of the rate increase, PacifiCare expects to post increased sales during 2006. The additional sales will be used to expand its membership and plan benefits. Analysts are expecting the company to post 2006 earnings of $4.42 a share on sales of $16.39 billion. Shares traded up $2.16 to $58.56.

Shares of

CuraGen

(CRGN)

fell 6.7% after the company said that Jonathan Rothberg would step down from his chief executive position. Rothberg, who will aid the company in its search for a new CEO, will continue to serve as CEO until a permanent replacement is found. "I am excited to be part of the company's search for a new chief executive officer with the experience, track record and commitment to turn our pipeline into drugs," Rothberg said. Shares traded down 26 cents to $3.64.

Exactech

(EXAC)

fell 10.8% after the company cut its first-quarter guidance. The maker of orthopaedic implant devices now expects earnings of 10 cents to 12 cents a share on sales that will fall to the low end of its previous guidance. Previously, the company forecast earnings of 16 cents to 17 cents a share on sales of $22 million to $24 million. Analysts had been expecting earnings of 16 cents a share on sales of $23.9 million. Lower-than-expected sales associated with supply chain issues - which the company is working to resolve - and lower gross margins led to the revised first-quarter outlook. Exactech will post first-quarter results on April 27. Shares traded down $1.84 to $15.25.

Shares of

EntreMed

(ENMD)

traded actively after the company said that preclinical data for Panzem, or 2-methoxyestradiol, showed promising results in reducing inflammation and halting disease progression in an animal model of rheumatoid arthritis. The company said that Panzem also exhibited disease modifying antirheumatic drug properties. EntreMed is currently evaluating Panzem capsules and Panzem NCD in phase I and phase II clinical oncology studies as well as conducting preclinical studies in inflammatory diseases such as rheumatoid arthritis. Shares traded down 3 cents to $2.19.

Other health care movers included

Pfizer

(PFE) - Get Report

, up 97 cents to $26.90;

Elan

(ELN)

, up 1 cent to $3.67;

Merck

(MRK) - Get Report

, up 54 cents to $33.04;

Johnson & Johnson

(JNJ) - Get Report

, up $1.03 to $69.01;

Schering-Plough

(SGP)

, up 52 cents to $18.50; and

Amgen

(AMGN) - Get Report

, up 53 cents to $57.86.