Updated from 1:44 p.m. EDT

Invitrogen ( IVGN) was among the worst-performing health and biotech stocks Wednesday after it reported in-line second-quarter earnings results on lower-than-expected sales. The drug-discovery software provider also warned that full-year sales would be lower than expected.

Excluding items, Invitrogen earned 74 cents a share during the second quarter on sales of $254 million. Analysts had expected it to earn 74 cents a share on sales of $261.5 million. Looking ahead, it reaffirmed its full-year earnings outlook but warned that it now expects sales of $1 billion to $1.02 billion, lower than the $1.05 billion analysts polled by Thomson First Call had expected. Shares of Invitrogen traded down $14.99, or 22.7%, to $51.16.

USANA Health Sciences ( USNA) rose after it reported better-than-expected second-quarter earnings and sales and upped its third-quarter and full-year outlook. During the second quarter, it earned 36 cents a share on sales of $67.2 million, easily outpacing analysts' expectations. Looking ahead, it now expects third-quarter earnings of 36 cents to 38 cents a share, in line with expectations, on sales of $69 million, which would be higher than the $66.1 million analysts had expected. For the full year it now expects to earn $1.42 to $1.44 on sales of $270 million. Analysts had expected it to earn $1.40 a share on sales of $261 million. Shares of USANA traded up 86 cents, or 3.1%, to $28.67.

Shares of Immucor ( BLUD) fell after the company reported better-than-expected fourth-quarter earnings and sales, but warned that full-year 2005 earnings could fall to the low range of analysts' expectations while sales will fall well short. The company reported fourth-quarter earnings of 11 cents a share, a penny better than expectations, on sales of $30.2 million, which outpaced analysts' expectations of $29.5 million. Looking ahead, however, it now expects full-year 2005 earnings of 64 cents to 67 cents a share on sales of $127 million to $130 million. Analysts had expected it to earn 67 cents a share on sales of $136.7 million. Shares of Immucor traded down $2.91, or 13.3%, to $19.02.

The Medicines Company ( MDCO) fell after it reported weaker-than-expected second-quarter earnings. The company earned 6 cents a share on sales of $34.4 million. Analysts had expected it to earn 7 cents a share on sales of $34 million. Shares of The Medicines Company traded down $3.37, or 11%, to $27.23.

Shares of Nabi Biopharmaceuticals ( NABI) fell after the company posted a wider-than-expected second-quarter loss. The company lost 30 cents a share on sales of $48 million. Analysts had expected it to report a loss of 8 cents a share on sales of $45.4 million. A big jump in research and development costs contributed to the weaker-than-expected second-quarter earnings. Shares of Nabi Biopharmaceuticals traded down $1.87, or 14.2%, to $11.26.

Other health care volume movers included ImClone Systems ( IMCL), down $15.29 to $65.44; Pfizer ( PFE), down 33 cents to $32; Schering-Plough ( SGP), up 21 cents to $19; Boston Scientific ( BSX), up 65 cents to $35.35; and Amgen ( AMGN), down $1.15 to $55.85.