EVANSTON, Ill. (AP) — An Illinois biotech company says it's shutting down its operations following last week's government rejection of its blood substitute PolyHeme. Northfield Laboratories Inc. announced Friday night it had "terminated the employment of substantially all of its operational and staff employees" at its manufacturing plant in Mt. Prospect and its headquarters in Evanston. The company says it's evaluating options for its future. PolyHeme is the company's only product. The Food and Drug Administration has said the blood substitute's risks outweighed its potential benefits. Shares of Northfield fell to 23 cents on Friday.