Ribozyme Pharmaceuticals Inc., of Boulder, Colo., promoted Nassim Usman to chief scientific officer and vice president, research and development.

Sagres Discovery Inc., of Davis, Calif., added David Ichikawa as chief business officer.

Santarus Inc., of San Diego, hired Christine Simmons as vice president, regulatory affairs and quality assurance.

Scion Pharmaceuticals Inc., of Medford, Mass., added Jeffrey Williams as vice president of corporate development, Nancy Stuart as vice president of strategic development and Patricia Abbott as head of operations.

Senetek plc, of Napa, Calif., chose Suresh Rattan to head the Senetek Research Professorship and the Danish Centre for Molecular Gerontology, University of Aarhus.

Serologicals Corp., of Atlanta, said its CEO and president, David Dodd, was elected chairman of the Georgia Biomedical Partnership.

Signature BioScience Inc., of Hayward, Calif., added Geoffrey Duyk to its board and Frances Heller as vice president, corporate development and legal affairs.

Syrrx Inc., of San Diego, appointed Keith Wilson vice president of technology.

VaxGen Inc., of Brisbane, Calif., named Carmen Betancourt vice president of regulatory affairs and quality assurance and Mark Busch senior director of quality assurance.

ZymeTx Inc., of Oklahoma City, named Craig Shimasaki chief operating officer.