* Nextel Communications signed a two-year extension of its contract with the General Services Administration for its cell phone and radio messaging services, which will add an estimated $200 million a year to the Reston-based wireless carrier's sales. The contract provides wireless services to all federal agencies, as well as state and local agencies with federal funding, and will be used for emergency communications. The contract could be extended for three additional years. Nextel was awarded its first GSA contract in March 1999. Company spokeswoman Audrey Schaefer said sales under the old contract far exceeded preliminary expectations. She declined to comment on how much Nextel has sold to the government to date.

* Guilford Pharmaceuticals of Baltimore said the National Institutes of Health will test one of the firm's drug compounds as a potential therapy for Parkinson's disease. The National Institute of Neurological Disorders and Stroke will fund the research into Guilford's compound, GPI 1485, and up to five other potential therapies.

* Hemagen Diagnostics, a Columbia biotech firm, said it was advised that its stock failed to meet the Nasdaq Stock Market's bid requirement and may be delisted from the small-cap market. The company said it requested a hearing with the Nasdaq Listing Qualifications Panel but, if delisted, will continue to trade on the Nasdaq Bulletin Board. Shares of Hemagen closed at 23 cents, down 2 cents.

Compiled from reports by Washington Post staff writers, washingtonpost.com and Dow Jones News Service