WALTHAM, Mass. (AP) — Scientific instrument maker Thermo Fisher Scientific Inc. said Tuesday that it has promoted Executive Vice President and Chief Operating Officer Marc N. Casper to the roles of president and CEO, effective Oct. 15.

Casper, who has served in his current roles since May 2008, will also serve as a board member.

Casper succeeds Marijn E. Dekkers, who resigned to take on the CEO role at German chemical and pharmaceutical company Bayer AG. Dekkers, 51, will replace Bayer's current CEO Werner Wenning on Oct. 1, 2010.

Wenning, who extended his contract by eight months until the end of next September, will step down shortly before his 64th birthday.

The company said Dekkers will join its management board at the beginning of 2010. It said that in a transitional phase he also will be the chief executive of its Bayer HealthCare unit — succeeding Arthur Higgins, who is leaving the company during the first half of 2010 "for personal reasons."

Bayer is based in the western German city of Leverkusen, and its products include Aspirin and the birth control pill Yasmin. The company had a net profit for the April-June period of €532 million ($774.65 million) on sales of €8 billion.

Bayer shares were down half a percent Tuesday, trading at €46.14 ($67.18) in Frankfurt.