Psychiatry - Research Publications
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ItemAbnormalities in Osteoclastogenesis and Decreased Tumorigenesis in Mice Deficient for Ovarian Cancer G Protein-Coupled Receptor 1(PUBLIC LIBRARY SCIENCE, 2009-05-28)Ovarian cancer G protein-coupled receptor 1 (OGR1) has been shown to be a proton sensing receptor in vitro. We have shown that OGR1 functions as a tumor metastasis suppressor gene when it is over-expressed in human prostate cancer cells in vivo. To examine the physiological functions of OGR1, we generated conditional OGR1 deficient mice by homologous recombination. OGR1 deficient mice were viable and upon gross-inspection appeared normal. Consistent with in vitro studies showing that OGR1 is involved in osteoclastogenesis, reduced osteoclasts were detected in OGR1 deficient mice. A pH-dependent osteoclasts survival effect was also observed. However, overall abnormality in the bones of these animals was not observed. In addition, melanoma cell tumorigenesis was significantly inhibited in OGR1 deficient mice. OGR1 deficient mice in the mixed background produced significantly less peritoneal macrophages when stimulated with thioglycolate. These macrophages also showed altered extracellular signal-regulated kinases (ERK) activation and nitric oxide (NO) production in response to lipopolysaccharide. OGR1-dependent pH responses assessed by cAMP production and cell survival in macrophages or brown fat cells were not observed, presumably due to the presence of other proton sensing receptors in these cells. Our results indicate that OGR1's role in osteoclastogenesis is not strong enough to affect overall bone development and its role in tumorigenesis warrants further investigation. The mice generated can be potentially used for several disease models, including cancers or osteoclast-related diseases.
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ItemGlutathione precursor, N-acetyl-cysteine, improves mismatch negativity in schizophrenia patients(NATURE PUBLISHING GROUP, 2008-08-01)In schizophrenia patients, glutathione dysregulation at the gene, protein and functional levels, leads to N-methyl-D-aspartate (NMDA) receptor hypofunction. These patients also exhibit deficits in auditory sensory processing that manifests as impaired mismatch negativity (MMN), which is an auditory evoked potential (AEP) component related to NMDA receptor function. N-acetyl-cysteine (NAC), a glutathione precursor, was administered to patients to determine whether increased levels of brain glutathione would improve MMN and by extension NMDA function. A randomized, double-blind, cross-over protocol was conducted, entailing the administration of NAC (2 g/day) for 60 days and then placebo for another 60 days (or vice versa). 128-channel AEPs were recorded during a frequency oddball discrimination task at protocol onset, at the point of cross-over, and at the end of the study. At the onset of the protocol, the MMN of patients was significantly impaired compared to sex- and age- matched healthy controls (p=0.003), without any evidence of concomitant P300 component deficits. Treatment with NAC significantly improved MMN generation compared with placebo (p=0.025) without any measurable effects on the P300 component. MMN improvement was observed in the absence of robust changes in assessments of clinical severity, though the latter was observed in a larger and more prolonged clinical study. This pattern suggests that MMN enhancement may precede changes to indices of clinical severity, highlighting the possible utility AEPs as a biomarker of treatment efficacy. The improvement of this functional marker may indicate an important pathway towards new therapeutic strategies that target glutathione dysregulation in schizophrenia.
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ItemMedial temporal lobe glutathione concentration in first episode psychosis: A H-1-MRS investigation(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009-03-01)Glutathione (GSH) is implicated in the pathophysiology of schizophrenia. Previous brain spectroscopy studies, however, have been inconsistent, and there is little data available from first episode psychosis patients. This study compared brain GSH in a first episode cohort (n=30) to controls (n=18), using magnetic resonance spectroscopy (MRS), examining a temporal lobe voxel. Short-echo (TE 30 ms) acquisition proton MRS was performed on a 3T clinical magnetic resonance scanner. Comparison of the first-episode and control groups' GSH concentrations revealed a significant main effect of group (F(1,46)=4.7, p=0.035), but no main effect of hemisphere (F(1,46)=2.3, p=0.137) or group-by-side interactions (F(1,46)=0.4, p=0.513). Medial temporal lobe GSH concentrations in the first episode group were 22% higher than those in the control group. This study provides further evidence of significant perturbations in brain GSH in first episode psychosis, and supports a broader involvement of GSH in the pathophysiology of schizophrenia.