* Celgene Corp., of Warren, N.J., used its chirally pure formulation of mexiletine to reverse in animal models the severe neuropathic pain associated with trauma, spinal cord injury and diabetic complications. An impure form of the drug already is marketed, and physicians sometimes use it as an oral adjuvant to opiates and nonsteroidal anti-inflammatory agents for chronic neuropathic pain. The purified form, however, behaves differently and may work with fewer side effects, the company said.

* Cel-Sci Corp., of Alexandria, Va., said the first four patients in a Phase I/II trial in Israel of Multikine, its mixture of cytokines, had substantial reductions of their head and neck tumors over a period of three weeks. Protocol required surgery or radiation to be conducted following the Multikine treatment. Pain also was reduced or eliminated, and some patients were better able to talk, chew and swallow. In another study, Cel-Sci reported, its herpes simplex vaccine protected against the infection in mice.

* PhyMatrix Corp., of West Palm Beach, Fla., said it expects to complete the acquisition of Clinical Studies Ltd. (CSL), of Providence, R.I., by Oct. 31. PhyMatrix will acquire all outstanding stock in exchange for about 5.2 million shares of PhyMatrix's stock issued to CSL shareholders. The transaction will be accounted for as a pooling of interests. CSL conducts geriatric, central nervous system and women's health research at 22 centers in 11 states. For the six months ending July 31, it reported revenues of $13.1 million.

* Stanley Prusiner has won the 1997 Nobel Prize in physiology or medicine for his discovery of prions, or proteinaceous infectious particles, which are believed responsible for illnesses that include Creutzfeldt-Jakob (or "mad cow") disease. Prions, which contain no DNA or RNA and are normally found in humans and other organisms, sometimes change their form and appear to convert other prions into different shapes, causing disease. Prusiner, professor of neurology, virology and biochemistry at the University of California, San Francisco, has received more than $56 million in research grants from the National Institutes of Health.