Shares of Martek Biosciences ( MATK) were among the best-performing health-related stocks Thursday, jumping 18% after the maker of algae-related nutritional products raised its first-quarter sales guidance.

The company now sees sales of $62 million to $63 million, up from an earlier view of $58 million to $59 million. Analysts polled by Thomson First Call expected sales of $58.4 million. Martek attributed the revised guidance to growth in sales of its core infant formula. Shares were trading up $5.07 to $33.26.

Shares of eResearch Technology ( ERES) slumped 17% after the supplier of technology used by biotech companies posted solid fourth-quarter earnings but warned that first-quarter results would be below forecasts. The company also said its chief executive will retire by the end of the year. For the fourth quarter, eResearch earned $5.3 million, or 10 cents a share, on sales of $25.4 million. Analysts expected earnings of 8 cents a share and sales of $24.5 million. During the year-earlier period, the company earned $7 million, or 13 cents a share, on sales of $27.1 million.

Looking ahead, eResearch sees first-quarter earnings of 5 cents to 7 cents a share on sales of $21 million to $23 million. The guidance excludes stock-based compensation costs, which will lower earnings by a penny a share. Analysts project earnings of 10 cents a share and sales of $26.8 million.

The company said that Joseph Esposito plans to retire as CEO before the end of 2006. "In addressing the company's future needs for pursuing our next phase of growth and profitability, both the board and I believe it is an opportune time for new leadership to take eResearch to the next level," Esposito said in a prepared statement. Shares were trading down $2.95 to $14.81.

Shares of Dendrite ( DRTE) fell 12% after the provider of software and services to the pharmaceutical industry posted fourth-quarter earnings that were below expectations. The company earned $21,000, or less than a penny a share, on sales of $108.4 million. On an adjusted basis, which excludes noncash amortization expense, the company earned $250,000, or 1 cent a share. Analysts expected earnings of 4 cents a share, with sales of $106.4 million. "The fourth quarter was a difficult experience as we did not execute properly and take full advantage of our many growth opportunities," the company said. A year ago, the company posted adjusted earnings of $9.7 million, or 22 cents a share, on sales of $104.8 million. Shares were trading down $1.76 to $12.60.

Charles River Laboratories ( CRL) shares moved higher after the company posted better-than-expected fourth-quarter earnings and in-line guidance for 2006. The company, which provides services for pharmaceutical companies, earned $50.4 million, or 69 cents a share, compared with $20.1 million, or 32 cents a share, a year earlier. Excluding items, earnings were 59 cents a share, topping Wall Street's projection by 2 cents. Revenue rose 22% to $291.2 million, surpassing analysts' target of $282.8 million.

Charles River expects 2006 earnings of $2.46 to $2.52 a share, excluding stock options expenses and one-time items. The forecast brackets analysts' mean estimate of $2.48 a share. The company's shares recently changed hands at $48.22, up $3.37, or 7.5%.

Conmed ( CNMD) dropped 12% after the medical equipment supplier posted fourth-quarter results that missed forecasts and warned that first-quarter results also would be weaker than expected. The company earned $2.8 million, or 10 cents a share, on sales of $153.2 million. Excluding items, Conmed earned $5.3 million, or 18 cents a share. Analysts expected earnings of 27 cents a share and sales of $160.5 million. Results were hurt by lower-than-expected surgical procedures, foreign currency translation, and extended capital equipment purchasing decision timelines in certain markets, the company said. During the year-earlier quarter, Conmed posted adjusted earnings of $14.7 million, or 49 cents a share, on sales of $161.2 million.

For the first quarter, Conmed projects earnings of 18 cents to 22 cents a share, below analysts' prediction of 38 cents. The company forecast sales of $153 million to $158 million, compared with Wall Street's target of $162.5 million. Shares were down $2.87 to $20.79.

Shares of Chattem ( CHTT) tumbled 12% after the seller of health products posted fourth-quarter earnings that were a penny short of forecasts. The company earned $2.4 million, or 12 cents a share. Excluding items, the company earned $8.6 million, or 43 cents a share. Analysts expected earnings of 44 cents a share. Sales totaled $63.9 million, just shy of analysts' projection of $63.7 million. During the year-earlier period, the company posted adjusted earnings of $7.2 million, or 35 cents a share, on sales of $60.7 million.

Looking ahead, Chattem sees 2006 earnings, before items and stock-based compensation costs, of $2.30 to $2.40 a share. Analysts predict earnings of $2.24 a share, including stock-based compensation costs. Chattem projects full-year sales of $315 million to $330 million, compared with Wall Street's forecast of $328.5 million. Shares were down $4.81 to $36.95.

Other health care volume movers included Pfizer ( PFE), up 37 cents to $26.74; Johnson & Johnson ( JNJ), up 53 cents to $59.13; Schering-Plough ( SGP), down 4 cents to $18.63; Boston Scientific ( BSX), down 1 cent to $22.22; Genta ( GNTA), down 18 cents to $3.16; Amgen ( AMGN), down 59 cents to $71.46; Bristol-Myers Squibb ( BMY), down 10 cents to $22.64; Elan ( ELN), up 10 cents to $14.50; and Merck ( MRK), up 17 cents to $34.46.

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