Health stocks kept slightly green Monday amid an array of news, including trial updates, turnover and turmoil in general.

First, Acorda Therapeutics ( ACOR) tacked on 25% to $27.20 Monday after the company said a study showed its experimental multiple sclerosis drug Fampridine didn't cause an increase in the electrocardiographic QT interval in comparison to placebo.

The Food and Drug Administration requires companies to conduct QT studies on drugs because changes to the QT interval, a measure of time between waves in the heart's electrical cycle, can indicate risk of cardiac arrhythmias. The company expects data in the second quarter of this year from a second phase III study of the drug, which is currently being studied for improving walking ability in people with multiple sclerosis.

Another stock up on high volume, Medivation ( MDVN) said that after discussing midstage trial results with the FDA it now plans to move Alzheimer's treatment candidate Dimebon into late-stage development.

The company is holding a conference call Monday at 4:30 p.m. to discuss the decision. Watch for more on Medivation and this call from TheStreet.com senior columnist Adam Feuerstein. Shares were up 12.2% at $16.66.

Meanwhile, inching down a few percentage points, Biogen Idec ( BIIB) said Monday that activist investor Carl Icahn has nominated three people to the biotech company's board.

"We are taking this action because we believe that Biogen's recent purported attempt to find a suitor was not conducted in a way to enhance the success of the endeavor. We believe that the process was flawed in a number of key respects and that the process was run to placate us and other large shareholders who we believe asked for Biogen to find a buyer," Icahn said in a press release Monday.

His three nominees include ImClone Systems ( IMCL) board members Alexander Denner and Richard Mulligan. Denner is Icahn's lead advisor and also a board member at Adventrx ( ANX), and Mulligan is the director of the Gene Therapy Institute and an endowed professor of genetics at Harvard. The third proposed addition is Anne Young, chief of neurology at Massachusetts General Hospital and the Julieanne Dorn Professor of Neurology at Harvard Medical School. Biogen ticked down 1.3% to $58.13.

On the ratings side, Jeffries and Co. analyst Eun Yang upgraded Medarex ( MEDX) to buy from hold, considering the long-term outlook for its cancer-treating compounds. The stock took a beating last December when the company's ipilimumab failed to affect any shrinkage of tumors in at least 10% of patients in a study reported. However, Yang noted that the drug could eventually show an improvement in overall survival rate.

Medarex is developing Ipilimumab with Bristol-Myers Squibb ( BMY) and is also entitled to a 15% royalty on sales of tremelimumab, a similar product that Pfizer ( PFE) is developing. Late-stage data on the class of drugs, known as CTLA-4 inhibitors, are expected in 2009, and with potential commercial launches that year or the next, Yang sees Medarex poised to receive $300 million in royalties annually.

Medarex shares edged up 4% to $9.59, but are still nearly 47% lower than the stock's 52-week high. Medarex, Biogen and Acorda are all components of the Nasdaq biotechnology index, which was up 1.1% at 800.46.

In other health stocks, Inverness Medical Innovations ( IMA) said Monday it will pay $900 million in stock and cash for Matria Healthcare ( MATR).

In-home medical care company Inverness will pay $6.50 in cash, plus $32.50 in premium-priced convertible stock, for each share of Matria, which specializes in women's health, oncology and disease management. Click here for more on the deal from senior writer Melissa Davis.

Inverness was down 8.3% to $47.88, and shares of Matria held near the flat line at $30.67 after trading a few percentage points higher earlier in the day.

And, elsewhere, managed-care provider WellCare ( WCG) ousted its three top executives amid a government investigation. The company said after Friday's amrket close that Chairman and CEO Todd Farha, Chief Financial Officer Paul Behrens and General Counsel Thaddeus Bereday will leave their posts, effective immediately.

WellCare named Charles Berg to the chairman post and appointed Heath Schiesser CEO. Berg is the former chief executive of insurance giant Oxford Health Plans, while Schiesser previously was an executive with WellCare and most recently an advisor to its Medicare prescription drug program.

The company, still searching for a new CFO, saw shares rise 11.5%, to $48.08. Click here for a bit more on the WellCare turmoil and turnover.

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