(Washington, DC) -- Oregon Senator Ron Wyden is asking the federal Centers for Medicare and Medicaid Services to review pharmacy closures nationwide. Earlier this year, Eugene-based BiMart announced it's closing 56 pharmacies in the Northwest and handing over the clients to Walgreens. BiMart cited increasing costs and reimbursement pressure as the reason. Wyden says he wants to know whether fees imposed by Medicare Part D and middlemen known as pharmacy benefit managers are driving the closures.