Peripheral-type benzodiazepine receptors in diagnostic subtypes of schizophrenic patients.

The peripheral-type benzodiazepine receptor (pBZD-R; also called the omega-3 receptor or the mitochondrial benzodiazepine receptor) seems to play a critical role in the production of neurosteroids, which are able to alter the electrical properties of neuronal membranes and thus the firing patterns of neurons. Putative endogenous ligands are the diazepam-binding inhibitor and its processing products, as well as porphyrins, some of them, in the case of porphyria, are well known to give rise to certain aspects of neuropsychiatric disorders, such as schizophrenic-like symptoms. Previous findings of altered benzodiazepine binding sites in post-mortem brain samples and platelets from small samples of schizophrenic patients have been inconclusive. Therefore we investigated characteristic binding parameters (Bmax, Kd) of the granulocytic pBZD-R by using the selective ligand PK11.195 in 53 subjects, fulfilling ICD-10 and DSM-IV criteria of schizophrenia. The binding parameters in our total group of 53 schizophrenic patients did not differ from those in healthy subjects. However, Bmax values were significantly reduced in schizophrenic patients with predominantly negative symptoms (residual type) compared to schizophrenic patients with predominantly positive symptoms, i.e. paranoid (-50%) and catatonic subtype (-38%). Moreover, only residual type schizophrenics exhibited a significantly reduced binding capacity compared to healthy subjects (-38%). More studies are warranted to clarify the functional significance of this binding site in the pathogenesis of negative symptoms.

Detection of antibodies to the recombinant P39 protein of Borrelia burgdorferi using enzyme immunoassay and immunoblotting.

The diagnostic value of serologic tests using the recombinant P39 protein of Borrelia burgdorferi was compared with that of tests prepared from a whole spirochete antigen source. Immunoassays (ELISA and Western blot) prepared from either the recombinant protein or whole spirochetes were evaluated using a test panel comprised of 2 sera groups, one obtained from patients with clinically diagnosed Lyme disease, the other from individuals with no indication of past or current infection with B. burgdorferi. Results obtained indicate that ELISA screening tests relying on the recombinant protein are less sensitive than ELISA tests using whole spirochete antigen preparations. Western blot tests based on the P39 protein were more specific than P39 ELISA yielding no false positive or indeterminate results. These findings suggest that the P39 protein may prove valuable for confirmation testing for Lyme disease.