Paratek Pharmaceuticals Inc., of Boston, appointed Ken Tanaka vice president of research and development.

Select Therapeutics Inc., of Woburn, Mass., added Darwin Prockop to its scientific advisory board.

Transkaryotic Therapies Inc., of Cambridge, Mass., appointed Anthony Murabito vice president, management information systems and promoted Daniel Geffken to senior vice president, finance and chief financial officer.

Valentis Inc., of Burlingame, Calif., added Alan Mendelson to its board.

Valigen N.V., of Newtown, Pa., appointed Bernard Bihain chief scientific officer.

Xanthon Inc., of Research Triangle Park, N.C., added Dwayne Allen to its research and development group as a senior scientist.