Upgrades and clinical data boosted a few biotechs while others were still afflicted by day-old news on an overall gloomy Tuesday for health stocks.

On the uptick, Arena Therapeutics ( ARNA) picked up $1.14, or 15%, to $8.55, after an upgrade from Bank of America analyst William Ho. He raised his rating on the stock to buy from neutral, predicting that a data safety monitoring committee reviewing echocardiograms won't find a link between Arena's obesity drug Lorcaserin and heart valve damage.

Also investigating safety concerns, Pozen Pharmaceuticals rose after announcing that it submitted data to the FDA from a short-term trial on its migraine drug Trexima. Specifically, no harmful mutations in white blood cells occurred when the drug was given to volunteers for seven days. The company and partner GlaxoSmithKline ( GSK) have suffered two delays from the FDA in light of safety concerns. Pozen was trading up 94 cents, or 7.9%, at $12.80.

Arena and Pozen weren't enough to prod the Nasdaq biotechnology index into the green - it sat down 12.44, or 1.46%, at 841.75.

Another company that's partnered with Glaxo, Xenoport, ( XNPT) said on Tuesday that in a late-stage follow up trial, experimental drug XP13512 reduced the relapse of patients with restless leg syndrome, a condition known for unpleasant or painful sensations in the leg resulting in the urge to move.

Twelve-week late-stage data will be reported later this quarter, and Glaxo is expected to file a new drug application for XP13512 FDA in the third quarter.

A bit of selling after the news dipped the stock on Tuesday -- it edged down $2.12, or 3.5%, to $59. Keep in mind, Xenoport shares have rallied nearly 120% since April when results of a 12-week phase III trial showed similar benefits of the XP13512 in treating symptoms.

Elsewhere, Lifecore Biomedical ( LCBM) said Tuesday that it will be acquired by Warburg Pincus for $17 a share in cash, a 30% premium over the average price of the shares for the last 30 days, valuing the company at about $239 million. The company expects the transaction will close before the end of the first quarter. Shares climbed $3.89, or 30.3%, to $16.73.

Separately, Lifecore reported below-consensus second quarter results. The company reported quarterly revenue of $17.3 million, and net income of $1.24 million, or 9 cents a diluted share, vs. $1.36 million, or 10 cents a share, the year-ago period. Analysts surveyed by Thomson Financial were expecting 11 cents a share, on revenue of $18.27 million.

And a few stocks that were on the move from day-ago news: Schering Plough ( SGP) and partner Merck ( MRK) fell for a second day after study results indicated that Vytorin, a combination of cholesterol drugs Zetia and a statin, did no better at reducing plaque in arteries than the statin alone. The companies are now conducting larger trials on the drug. Schering gave up $1.34, or 5.2%, to $24.20, while Merck was trading down $1.38, or 2.3%, at $58.40 on Tuesday.

Also, Monday post-close Genentech ( DNA) gave its quarterly and year end results. The company met and beat earnings expectations, but fell a bit short on sales of its two lead drugs, Rituxan for non-Hodgkin's lymphoma and cancer drug Avastin.

For the year, the company earned $3.1 billion, or $2.94 a share, compared to $2.3 billion, or $2.23 a share in 2006. For the fourth quarter, Genentech reported adjusted earnings of $737 million, or 69 cents a share, on revenue of $2.96 billion, beating Street expectations of $720 million, or 68 cents a share, on revenue of $2.9 billion.

However, the company reported $596 million in sales for Rituxan and $603 million for Avastin, while analysts had anticipated $603 million and $616 million, respectively. Shares were trading down 88 cents, or 1.3%, at $69.76 on Tuesday.

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