* Oncogene Science Inc., of Uniondale, N.J., repurchased 1.25 million shares of its stock from Becton, Dickinson and Co., of Franklin Lakes, N.J., for $8.75 million. Becton bought the shares in 1991 as part of a collaboration with Oncogene on cancer diagnostics.

* Agouron Pharmaceuticals Inc., of La Jolla, Calif., submitted a marketing authorization application in Europe for Viracept (nelfinavir mesylate), a protease inhibitor against HIV. The company filed a new drug application for Viracept with the FDA in December 1996.

* Seragen Inc., of Hopkinton, Mass., agreed to sell its manufacturing and clinical operations facilities for $5 million to Boston University. Seragen said the deal is the first in a series of moves to raise money. The facilities will continue to manufacture Seragen's drug candidates on a contract basis.

* Shaman Pharmaceuticals Inc., of South San Francisco, began a Phase II trial of Provir for watery diarrhea. The placebo controlled study will enroll 700 patients. If successful, a Phase III trial may begin later in 1997. Provir, an oral drug, is derived from an extract of the croton plant, found in Latin America. Traditional medicinal uses of the plant include treatments for respiratory diseases and gastrointestinal disorders.

* Life Medical Sciences Inc., of Edison, N.J., began clinical trials of Repel, a bioresorbable polymer for prevention of post-operative adhesions. The device will be evaluated in gynecological surgeries.

* Chiron Corp., of Emeryville, Calif., and its joint business partner, Ortho Diagnostic Systems Inc., of Raritan, N.J., signed an agreement to provide reagents, systems and support to the American Red Cross to screen blood supplies for viral diseases. Ortho Diagnostic is a subsidiary of Johnson & Johnson, of New Brunswick, N.J.

* NeXstar Pharmaceuticals Inc., of Boulder, Colo., will receive $2.4 million a year, a $1.4 million increase, in an extension of a 1993 agreement with Schering AG, of Berlin. The two companies are developing in vivo imaging agents using NeXstar's Selex combinatorial chemistry process. NeXstar's technology creates libraries of oligonucleotides. The nucleotide molecules, called aptamers, are targeted for development as drugs and diagnostics.