RICHMOND A St. Petersburg-based private drug treatment center that faced allegations of patient abuse has closed its Virginia operation, state officials said Monday. The Springfield office of Straight Inc. closed Friday, the state Department of Mental Health, Mental Retardation and Substance Abuse Services said. Straight Inc. has used a variety of controversial mental and physical techniques to deter children from drugs. The program's philosophy includes breaking down patients' defenses about drug use, a process critics have said can be demeaning. Company spokeswoman Joy Margolis said 60 percent to 70 percent of patients do not return to drug use after participating in the program. The program had worked to correct several violations, includi ng physical restraint of rebellious clients, but still faced problems in renewing its license, said Jacqueline M. Ennis, assistant commissioner of the state agency.