Correlation between plasma homovanillic acid concentrations and severity of schizophrenic symptoms: A reflection in an independent sample : Rene S. Kahn, Michael Davidson, Rami Kaminski, Peter Powchik, Robert McQueeney, Philip D. Harvey, Farooq Amin, Seth Apter, Patricia Warne, Stacey Jaff, Kenneth L. Davis Bronx Veterans Affairs Hospital, and Department of Psychiatry, Mount Sinai Medical School, New York, NY 10029