A nationally prominent physician and advocate for single-payer healthcare assailed the power and influence of the insurance and drug industries in a speech Thursday at The Rotary Club of McMinnville.Dr. Garrett Adams, past president of the 20,000-member Physicians for a National Health Program, took aim at health insurance giant Aetna for “manipulating the federal government” by threatening to abandon hundreds of thousands of customers who bought their plans with subsidies under the Affordable Care Act, familiarly known as Obamacare. Aetna and others, such as BlueCross BlueShield of Tennessee, have asked state insurance regulators for dramatic increases in premiums for policies issued under President Obama’s massive 2010 health care overhaul. In practically all cases, those price increases were approved, and policyholders may expect scorching premium hikes starting in January.