MADISON, Wis. (AP) – Enrollment in the new online health insurance marketplace begins in just one week, and those who will work closely with the new exchange are slated to give a status update on Tuesday.  The marketplace, or exchange, was created under the federal Affordable Care Act. It is designed as a place to shop for insurance.   About 500,000 Wisconsin residents currently without insurance, or losing their state Medicaid coverage, are expected to shop for federally subsidized plans sold through the exchange starting in October. The plans take effect in January.  Wisconsin Health News scheduled a Tuesday seminar with three health care leaders to discuss issues related to the exchange starting up.  Speakers include the head of the Wisconsin Statewide Health Information Network and the president of Agnesian HealthCare.